Well, if Lydia wanted you to be her personal dress-up doll, then you’d become just that. After you made your choice, the message “Transformation In Progress…” appeared on screen with a progress bar.
The bar began to move and alongside it the first changes started. The world around you became slightly bigger, as your height decreased. Your body fat relocated from your waist to your breasts and hips for a nice hourglass figure, gifting you with two nice handfuls of breasts and a sizable behind. Between your legs your equipment was sucked inward and replaced by a slit.
With the exception of the top of your head, all your body hair disappeared. Your limbs thinned into more feminine configurations with slender hands and dainty feet. The hair on your scalp increased in length until the straight raven locks reached the small of your back. You tentatively closed your eyes, as you felt the changes in your face begin to start.
When you opened them again, you almost blushed at the beauty standing in the mirror before you. Large, blue and very expressive eyes with long eyelashes, cute little lips, a small button nose and no sign of facial hair. You looked like an anime girl turned real.
But the progress bar was only half full and not too soon after the second set of changes began.
You felt your movements getting stiffer and stiffer, as you watched your skin harden into a durable porcelain. Your breathing ceased, as you lost any need to do it due to your body becoming hollow. A serene smile settled on your face right before your facial muscles vanished, permanently freezing it into this expression. All the joints of your body were replaced by clearly visible ball joints, ironically giving your limbs even more freedom of movement than your former human body did.
Your clothes began to shift. Moving and weaving until they became a perfect replica of the monster girl café uniform Tanya was wearing, with a short skirt, corset and a fitting headdress. Even your shoes morphed into black mary janes.
With that the progress bar reached its goal and the end of your transformation was announced. With perfect poise and grace only a bisque doll was capable of, you turned to the side and walked out.
Once you left the booth, you could see Lydia already waiting for you outside. She gave a wolf-whistle at seeing you.
“Damn girl, or should I say, dolly. Didn't expect you to literally become my puppet. You set the bar so high, I’ll have to choose something special now.” With those Lydia entered the full immersion booth herself.