They start gently, making the soon-to-be toy feel comfortable, at ease. Just a few tender touches, a gentle massage here and there.
As they become accustomed, they slowly move further, gauging responses to not overstep. Gentle caresses of the genitals, maybe slightly rougher groping, humming sweet nothings into their ears.
When they've been sufficiently excited, they begin proper genital stimulation. Slow at first, gradually increasing speed and intensity. They hold onto the cuties body, anchoring them with a firm touch.
Somewhere around this time, they're likely to cum for the first time. This is followed by a short break, and the nanobots whispering affirmations into the subs ears. Some already admit at this stage that they are sluts at heart.
Either way, the fucking will start again. This time the sub will be hopelessly over-stimulated. They will cum over and over, intensity increasing every time. The bots will continue mercilessly pounding them until they are completely tired out.
Then, the exhausted cutie will be gently cradled. Slow, rythmic pulsing will help them come down from the high. A small injection of chemicals will make them fall into a deep, long, restful sleep.
They are awoken by a steady fucking. Their sleepy bodies won't fight; they will just embrace the pleasure.
The next step is crucial. As they are enjoying their treatment, two tentacles of nanobots worm their way into their ears and make their way into the cranium.
They coat the axons, inset themselves into synaptic clefts, and replace some neurons entirely. Brain signals are recorded, responses tested, memories catalogued, and eventually a neural communication link is established.
Subjects describe that this process causes immense pleasure, combined with a temporary "mind blanking" effect as their brain is integrated.
Further nanobots are injected into the cutie, performing various body modification in accordance to their owners and - within reason - their own wishes.
An advanced custodian AI is uploaded into the computer-enhanced brain, which has many functions such as providing emotional assurances, guaranteeing good behavior, overriding limb control if desired, and everything else one would expect from a mind-computer-network interface.
To celebrate their conversion into a toy, the AI searches the memories for their deepest desires and formulates a customized fucking experience to cater to them.
Once they have been given the appropriate pleasures, they are given another rest before their future duties and expected behaviors are explained to them.
A wide variety of education programs can be run at this stage, should the owner desire specific skills, although most opt to teach their new toys themselves.
Once they toy is finished, they are lifted from the vat and packaged in a set of standardized simple clothes. Instead of shipping, toys are tasked with delivering themselves to their new owners, their AI assisting with navigation around unfamiliar public transport.
After the toy rings the doorbell and is received by their new owners, most are eager to unwrap their new toys (or, in most cases they,simply tear off the packaginh) and perform an extensive test of all functionality.