As Jon tried to leave the machine, the AI spoke.
"Would you like to set a duration for this transformation?" A slider appeared in front of Jon, hovering in mid-air. "The duration is a minimum time. You will not be permitted to alter any transformations you have already made before this time has elapsed, although you may add new changes. After the time has elapsed you may return to your previous body or make any new transformations you wish.
Jon stopped to think. This had always been his fantasy, to be turned to into a sexy girly girl. Part of the allure for Jon was being 'forced' to act the part, with the behaviours and mannerisms of a girl.
While Jon recognised that this was just a fantasy and actually living this life he had created was very different to simply letting his imagination run wild with no consequences, he at least wanted to get the full experience. He didn't want to be able to chicken out.
He knew he could choose not to set a duration at all, and then after seeing if he did like the changes he could come back and set a longer duration.
At the same time, the thought of having to live out this life was his fantasy, and part of that was being forced to be this girl. In fact, just standing here in this new body was turning him on.
He put his finger on the slider, and made his decision.