This was a pretty good read. As you asked, I'd have to say my favorite part was the ending, even if only due to the lack of animal abuse(sorry, just not my thing). If you continue this, you should provide more detail about what happens as opposed to just skimming over the entire procedure in a sentence or two. What you could do is give the machine a "manual" mode, so scenes last longer and you can add detail. Something else to consider is whether the machine can combine things together instead of just taking them apart. As for things I'd like to see, you could have some nipple/urethra/navel penetration along with perhaps some ovary and fallopian tube play. Another thing you could add could perhaps be a lobotomy scene.