"Test number 43, solid steel bolt." intoned Dr. Paul Schaefer, speaking at the video camera acting as his experiement log.
He placed the metal bolt (on loan from the mechanical engineering lab across the hall) on the table next to the red and white gumdrop-shaped machine he was testing.
"Activating duplicator..." he said, trailing off as he lowered a protective screen over the table. The screen in place, he hit the button to turn on the machine and watched it go.
A low electric hum filled the air and the machine started to glow out a few clear ports in the side. Suddenly, with a tiny "pop!", another bolt flashed into existence on the other side of the machine. Dr. Schaefer, a doctorate before he was even 25, pumped his fist in the air and turned off the machine before it duplicated another bolt and raised the shield. He picked up the new and old bolts and found them indistinguishable, save for the fact that one was in his left hand (the new bolt) and one in his right. Smiling to himself, he placed the old bolt back on the table and stopped the recording on the camera before heading across the hall to "return" the new bolt.

Unbeknownst to him, a stealthy form snuck into his lab as he was leaving. This stealthy form crept across the lab, curiously peeking into boxes of parts, glancing over documents strewn about the room, before finally reaching the experiment table and finding the duplication device.
"Aha!" the form cried to itself before grabbing the device.

Paul returned from his friendly visit to the mechanical lab rubbing his hands with glee. They hadn't suspected a thing, even when they closely inspected the bolt for signs of degredation. His machine had worked perfectly! He was so gleeful that the fact that his machine was missing and a cute girlfriend rested on the table it had been occupying didn't register at first. Humming to himself, he connected the camera to his computer and started offloading the footage for filing away with the other footage. Turning to the experiment table, he bent over slightly and extended his hands, expecting to pick up the machine, only to have his hands impact his girlfriend's chubby belly instead.
"Hee, that tickles!" she giggled, then kissed his confused face on the forehead. "Hey there, babe, we should probably head home before you get handsy!" she teased.
"Kat! W-where's my device!" he asked, frantic. "Did you see my device here?"
"I didn't see any device, but I did see your valentine's gift. It didn't taste very good though, pretty plasticy... Pretty colors though!" she replied.
Paul stared at her, mouth agape. Closing his mouth slowly, he recovered enough of his senses to ask, "You mean... you ate the red and white device on the table here?"
"Yep! I'm starting to think maybe it wasn't your valentine's day gift."
"It was not..." he muttered, his hand going to his brow and rubbing intensely.
"Oh, pooh. I know you forget every year, but really, we have calendars!" she joked, patting him on the back.
"No, it was the culmination of months of work! Ugh... Well, at least making another one shouldn't be too hard. Everything is worked out, I'll just need to plead with the department to give me another brick of plutonium. The video should be worth that much..." he continued muttering.
Just then, both Paul and Kathleen's stomachs grumbled, reminding them that lunch had been over four hours ago. Paul sighed and put his arms around Kat.
"I guess there's nothing to do for tonight. Come on, let's go home."

The two of them trooped home, Kat far more exhuberant than Paul (though to be fair, he had just lost a fully working prototype). Kat's smile grew larger and larger the closer they got to the front door until her face was practically split in two by her mouth. Paul eyed her warily as he slid the key into the lock and turned, only to have his face turn into a mask of surprise as a giant teddy bear forced its way out the door and onto him, overbalancing him and causing him to fall on his butt with a mountain of bear on top of him.
"Happy valentine's day, love!" Kat shouted and dove on top of the teddy bear on top of Paul, hugging it tightly.
From underneath the teddy bear, Kat heard a muffled groan before being lifted up by Paul extracting himself from the pile.
"Oof, you don't pull any punches." he stated, chuckling.
"Not a one!" she laughed, rolling off of the bear and helping him push it back inside.
Inside they settled down into the normal nightly schedule they had developed. Kat set the table while Paul warmed up some leftovers. After dinner was TV time cuddled up on the couch, their favorite time of the day. Sometimes they'd watch broadcast TV or prerecorded shows, but tonight was movie night, and so they settled in with the expectation they would be there for hours.
Shortly after the title screen, however, unbeknownst to either of them, something in Kat's stomach went "pop!". It coincided with a subtle increase in her waistline as the device inside of her malfunctioned and duplicated the fat surrounding it. A few minutes later, it did it again, duplicating the already duplicated fat and creating a less subtle increase in her waistline.
The effects continued to accumulate as the minutes ticked by, causing Kat's shirt to ride up further on her burgeoning belly every time the device activated. Every time the machine activated, the effects spread, spreading from just duplicating her belly fat (by the third pop, already eight times the size it used to be) to also duplicating breast fat, and soon to her butt and legs. Half an hour of this activation, the sound drowned out by the action onscreen, and Kat had gained fifty extra pounds, most of it in her belly but a sizeable portion in her breasts and butt. She remained oblivious, as did Paul, so rapt was their attention on the screen.
The sixth activation, however, marked the turning point, as that was when Kat noticed her bra getting uncomfortably tight. Not knowing what caused it but feeling in the valentine's day spirit, she slid a glance sidelong at Paul and pretended to casually take off her shirt, tossing it aside and leaning into Paul's side. When no attention was diverted, she grabbed his hand and slide it across her back, rubbing it against her bra clip.
"Wh-wha- oh. Ohh." he said, his attention finally caught. With a sidelong glance of his own his fingers found the clip and undid it, rubbing her back under it while she shrugged out of the offending garment. Both of them shucked their remaining clothing until they sat curled together in their underwear, enjoying the warmth of each other's bodies. In the darkened room, Paul failed to notice that his girlfriend had acquired much more padding in the past half hour than she had put on in all their three years of being together, but that was soon to come to an end.
A mere minute after their clothes had been discarded, the machine activated once more and doubled all the fat in Kat's body, instantly ballooning her from a chubby but curvy 170lbs to a much more chunky 220, the extra weight immediately apparent to both of them.
"What?" Paul said, his lap now full of Kat's belly that had a moment ago been mostly empty.
"Woah..." Kat cooed, exploring her new breasts that completely filled her hands.
They both stared at Kat's body, the movie temporarily forgotten, Kat with a sort of happy bemused expression and Paul with a mildly alarmed one. Kat had always been a bit chubby but nothing like this, and she certainly hadn't gained all that weight in the past few minutes. As the two spent a minute wondering how this was happening, the device activated again, the "pop!" heralding another duplication. Kat's body surged outward, her belly completely covering Paul's lap and her breasts overflowing her hands, now buried under her breastflesh.
With his attention fixed on Kat, Paul finally heard the faint sound of the device and realization dawned. As did horror.
"Kat I think the device I made is duplicating your fat and I don't know how to stop it." he said, deadpan, his face frozen into a horrified rictus.
"I don't think I really mind, babe..." she replied dreamily, a faint smile on her face.
Paul stirred himself into action, not sure what to do but needing to do something. Extricating himself from underneath Kat's belly was his first priority and proved easy enough at its present size. He didn't trust it to stay that size, however, and he wasn't about to find out from underneath it. He pulled his arms up from underneath Kat's belly and lifted, letting him swing his legs out and let her belly go, which landed with a satisfying plop on the couch where he used to be. He stood up before her and surveyed the situation, which was mostly normal except for one variable: Kat.
Kat's present weight was probably near the upper edge of 200, and it was only going to get worse unless he could think of a way to stop the duplicator. The only way out of this mess he could think of was deactivating the device, but the remote was back in his lab, and even then Kat's stomach acid might have eaten away that part of the machine. While he tried to think of how to fix everything, the device activated again with a "pop!", pounds magically adding themselves to Kat's already pudgy form at a breakneck pace. Where once there was only a little pot belly, now there was a large apron that hung over her lap, supporting two growing watermelons tipped by rosy button nipples. Chunky legs extended out from under the apron, their softness mirrored in Kat's arms which rested between her apron and breasts.
"Kat, we've got to stop the device you ate!"
"Why?" came the reply, her bright eyes half lidded but still sparkling.
"Because you're huge!" Paul returned, indicating her belly apron.
"Why is that bad?"
"What do you mean why is that bad!"
"You always said you loved my chub, now there's a lot more of it!"
Here Paul had to pause and admit to himself that he wasn't all that opposed, at least for now. He continued,
"Yeah, but at your current rate you're going to outgrow the house in like 10 minutes!"
As if on cue to punctuate his point, the device activated again, turning Kat's apron into a waterbed mattress with matching pillows and pushing her off the couch with a butt to match. Paul was almost knocked off his feet by the advancing wave of fat but managed to step back in time to avoid it, but the distance between Kat's belly and the TV was quickly shrinking.
"If you made one, you can make another, and then you can duplicate the house!" said Kat, smirking.
"You'd still be bigger than the house!" he replied, still upset but beginning to grin himself.
"Well then I guess you'd have to live in the house and I'll live next to it. And I can finally eat all five gallons of ice cream at once like you never let me before!"
The two grinned at each other and then burst out laughing, the issue of Kat's expanding body made much less stressful.
"Being realistic, babe, we have to do something about it soon. You really will outgrow the house in less than half an hour."
"Also being realistic, you can just duplicate something valuable and pay it off easily.", she replied, adding thoughtfully, "Though probably not money, I think that's forgery..."
Paul considered this, tapping his chin. He wasn't sure why he hadn't thought of it before, he had the goose that laid the golden egg in his hands, metaphorically speaking. If it could duplicate steel bolts and even the body fat within his girlfriend, it could just as easily duplicate gold, jewels, oil, anything valuable. He'd struck it rich without even thinking about it. Things were looking a lot rosier.
The device activated yet again, displaying its penchant to punctuate thoughts (as if it were a plot device), and caused Kat to expand once more. Her mattress of a belly exploded outward into the size of a small pool, growing in all directions and causing her breasts to splay outward slightly. With no warning, Paul was caught by surprise and shoved off his feet, landing face first on the newly grown belly, carried aloft and left staring up Kat's cleavage to her rosy cheeks. The growth continued as the fat was faithfully duplicated, Kat's belly growing out from being the size of a kiddie pool in the middle of their living room to squish up against the TV and then upward, the mound of fat carrying both Kat and Paul off the floor. Her breasts, partially grown watermelons before, surpassed fully grown and began heading for blue ribbon prize pumpkins, their strawberry nipples growing into soda cans and resting on Paul's shoulders.
"We should really do something about this, babe." Paul remarked, stroking her belly under him gently.
"Yeaaah, I guess so..." Kat admitted.
"Tell you what," Paul began, lifting himself off of Kat with a bit of difficulty due to the squishy surface of her belly, "I'm going to quickly head back to the lab and retrieve the remote. Try not to outgrow the neighborhood by the time I get back, ok?"
Kat smirked and replied, "Well I can't really help it, but I'll try!"
"That's my girl." he said, leaning in from her side to give her a quick kiss. He grabbed his keys from off the side table, only inches from the edge of Kat's belly, and burst out the door just as he heard a distinctive "pop!" sound from in the living room. He tried not to think of how much the TV cost.

The trip to the lab was uneventful and quick. Paul snatched the remote from off his desk and hurried back to his car, unsure of what he would find when he returned. The entire round trip normally took a full half hour, but since it was late and Paul was in a hurry, it took him only 20. 20 minutes was all it took, however, and when Paul pulled up into his driveway, he was greeted with the sight of a rubble pile with Kat in the middle of it. She was, quite literally, mountainous, her smiling face looking down on him from atop the mound of fat that was her belly, a full ten feet high and fifty feet around, a cavernous belly button you could keep a refridgerator in facing the driveway. Also (mostly) facing the driveway were two tanker trucks masquerading as her breasts, thir humongous weight causing them to slip off of her belly slightly and slide down to the sides. Paul couldn't be certain but the pinkish-brown areolae that topped them (themselves impressive puffy cones, bumpy and supporting nipples the size of propane tanks) looked slightly moist in the light cast by the streetlights. He couldn't see it directly, but he could tell that Kat's ass was as large as her breasts, maybe slightly bigger, just from the shadows that jutted out from behind the mountainous belly.
"Hey babe!" Kat called down from on high, "Bring me a treat?" she asked with a laugh in her voice.
"No treats, only this remote, though after the machine is turned off I can go get you some chocolates." he replied, waving the remote.
"Ok, well you better use it quick, because the last time it activated was-" she started, only to be cut off by a very muffled "pop!".
Kat's already humongous form sprang outward, doubling in size and completely destroying what was left of the house, as well as impacting Paul and pushing him out into the street with an avalanche of belly fat. Thankfully for their neighbors, the house that the two shared was on a very large plot, otherwise their houses might have been disturbed by the latest expansion. As it was, Kat's belly occupied almost all of the land on the plot, developing several folds in the process and deepening the already existing ones above her belly button (which now could easily hold Paul's car). Her already magnificent breasts doubled in size as well, still supported by her belly but drooping slightly lower. The sheen Paul had noticed earlier was extremely evident now, he could even see droplets forming at the ends of the phone booth nipples and bumpy areolae.
Paul's jaw dropped as he looked up at her humongous form, stupefied into inaction. Kat giggled and finished her sentence,
"only a few minutes ago. You should probably hit that button soon if you're going to, hon. I don't mind getting bigger, you have no idea how amazing it feels, but the neighbors might!"
Kat's voice broke him out of his shock and he quickly mashed the button that deactivated the device. The confirmation light on the remote blinked on and he sighed, releasing tension he didn't realize he had been holding.
"All done, dear, you won't be getting any bigger." he said, walking over to Kat's belly and sitting against it.
"Tonight at least!" she called down, a hint of mischief in her voice.
"We'll see about later, but yes, for tonight at least."
"Come up so I can see your handsome face, love!" she called back, with a sound like she was slapping her belly lightly to indicate where he should be.
"Alright, I'll be right up." he replied, and started his way up the mountain of a belly. The folds of her belly fat provided good handholds, though he almost fell into her cavernous belly button at one point due to a misplaced foot. A few moments of climbing (over first her belly and then between her breasts) and he was face to face with his girl, her form very different from even an hour ago. Even putting aside the massive breasts, belly, and butt, she was pudgier all over, with thick arms and legs and a softness to her face. The aforementioned assets dwarfed everything about her, though, and the rest of her body could easily be believed to be that of someone that weighed only two hundred pounds rather than several tons.
"Well babe, how do you like the new me?" she asked, her eyes lidded and her smile sly.
"You know I love it, babe. Now that you're not growing anymore I can appreciate it as it is without worrying about you getting any bigger and knocking over houses!" he said, laughing.
"If only I could, love, I kinda want to, just to see how big I could get! Not if anyone was inside though, that wouldn't be good..."
"I'll buy us a nice spot in the Amazon and you can get truly huge, how's that sound?"
"I'm going to hold you to that!" she admonished, mock serious and chiding.
The two laughed and hugged, Paul buried up to his waist in cleavage.
After that, there wasn't much to say. Both realized that it was a time to be quiet, the calm after the storm, and so Paul lay down between her breasts while she relaxed and lay on herself. Paul had to admit to himself that all in all, it wasn't a bad way to end valentines' day. He had several hundred times more girlfriend than before, which wasn't really a problem so much as a challenge. A challenge that he was personally well equipped to deal with, considering he alone now held the secret to duplicating matter. Things worked out pretty well indeed.
He got up from his spot and kissed his angelic girlfriend, throwing his arms around her shoulders.
"I love you babe." he said, "Happy valentines' day."
"I love you too, love, happy valentines' day."
And the two of them fell asleep there, exhausted from the events of the evening. Things would have to be done in the morning, but they could wait.