Why not try on a whole body altogether? So off Nate went with his freakishly huge hand to collect the necessary parts: the other hand, arms, legs, feet, and a torso, not bothering to pick up a head yet. He didn't exactly bother matching but it still took a while since some parts were heavy, especially the torso which he dragged from one of the lower shelves. He eventually had a heaping pile of man beside the bed, now for assembly. Nate got undressed removing his shirt, pajama bottoms, and underwear to reveal his skinny, hairless frame and undeveloped genitals. It was cold but he was too excited to care and got to work.
Nate got as far as putting the arms and legs on until he eventually ended up with the problem of the torso. Nate was a pretty clever kid though and wondered if you could put pieces together even if they weren't attached to him. A quick test with his old arm and his theory was true, it attaches onto the toned torso before him. Back to work he went putting his arms and legs onto the dummy torso, putting his old parts back on so he could work until it sat there, a headless mannequin. There was no hesitation as Nate popped of his head and neck and put it on the body from behind. His old body collapsed without its controller and his new body soon began to move.
Nate got up onto wobbly legs as he wasn't accustomed to his new height yet. It didn't take long for him to start walking about and getting in front of the mirror in the corner of the room. He giggled at the sight of his puny head on top of this grown up body and burst out laughing when he saw that he forgot something, his peepee. His laughter soon halted as he was struck by the sudden urge to pee. Nate ran for the bathroom on the first floor, getting sprayed again on the way out, only to come across a problem, he didn't have his peepee to use. He dashed back downstairs, pulled the book, ran inside, grabbed the closest one he could get, stuck it on, and ran back to the bathroom almost peeing himself. Soon, relief came and he sighed with his still young voice.
He walked over to the living room couch to examine his new member, he realized that it was huge compared to his old one, gigantic even. It was easily the size of his 10 year old arm. He gave it a tug but it wouldn't come off. He got a bit nervous so he went back down to the room and was greeted with the spray again. A quick tug and it popped right off. As Nate put his new buddy back on he realized something was out of place, the things that hung under it weren't there. He thought it looked kind of weird and felt a little empty so he got up to get a pair. Looking around a bit, Nate saw the biggest set and picked them up. each one was about the size of his new fists and it felt like the bag thing was really loose around them. he pushed and rotated them until they finally attached comfortably hung between his legs. He was then hit by weird feelings down there as soon as the testicles attached themselves.
His peepee got hard and bigger, rising to meet him inches from his face. He tried to push it down only to feel a big wave of the weird feeling and it felt good. Nate touched his penis all over and eventually got to rubbing it, sending more pleasure to his brain than it could handle. He exploded immediately in his first orgasm and white goo shot out of his penis from his churning balls coating his face and raining down onto his 10 year old body. He passed out on the bed while his penis kept leaking all over his body, slowly softening back to its original size. Nate lay there in sleep with a smile on his still young face...