Erin saw some option for something called Puberty. Her father had often taught her to try to be open minded to new things, and while not understanding what she was doing she tapped the "puberty, on" option on the floor. She wondered what would happen next.
The machine whirled and said "Thank you for your input, changing now!" The sides of the machine then started to glow an odd light. It wasn't blinding light, just a warm glow that bathed Erin in a light of change. Erin let out a little yelp as she felt her nipples grow sensitive. A small mound of flesh also started to pile up underneath her nipples. While her boobs only grew to an A-cup proportionally they were fairly large on her, not to mention their sensitivity and perkiness. Thanks to that part of the transformation she didn't notice her hips and butt also grow larger, and her pussy grow a little hairy. Finally she was able to start having children. The glowing stopped and the machine said "Thank you! please come again tomorrow!" Erin took a better looked at her body, it was mostly her groin and chest that changed however there were a few other more subtle changes. She felt a little taller, and when she looked at herself in the glass door's reflection her face looked different... a little more mature.
Erin said to herself "wow..." she then covered her mouth as she found even her voice was a little different. A little less high pitch she guessed. She exited the machine and then attempted to go back in, but the machine wouldn't allow her.
A voice of her father played from the machine and said "Due to the odd effects of this machine I cannot allow any person to use this more than once a day. Please understand." She wanted to say "but I want to go again!" however she realized it was a recording, she couldn't argue or force the machine to do anything. However she could still look around her father's gadgets... then again she should probably tell her mom about her little discovery and changes.