Hi Anon! I’ll try to explain it to the best of my ability since it’s so difficult to find information on it due to its rarity.
The first thing that should be known about self-stitching (also known as skin-sewing, self-sewing, etc) is that it is NOT a a form of self-harm. It is a body modification that can be temporary.
One of the best features of body-sewing is that it can be safely done for free at home, with just a needle and thread, color of your choice!
A good way to safely perform skin sewing at home is with a super small sewing needle. The smaller, the better in my opinion. It makes it much easier to pierce the skin while getting the large part of the needle and thread-knot through without messing up. But make ABSOLUTE SURE that the needle is sterilized just in case you pierce through too deep, or enter your bloodstream.
For areas like your palms or soles of your feet (or anywhere with callous) it’s easy to sew through the callous. From my own personal experience, it’s relatively painless as long as your don’t accidentally go too deep. If you notice you’re drawing blood or an excess amount, you may not be doing it correctly. Be very careful if you’re doing sensitive areas like the eyes, mouth, or near veins.
To remove, either pull out the thread from one stitch to another, or you can cut the thread and pull it out piece by piece.
A lot of people practice sewing their eyes or mouth shut, but that’s a little risky.
Something great about skin sewing is that it barely scars at all. In fact, there may be no scars at all if you’re doing it correctly. :) Also, if you doubt you’re artistic ability, you can sketch a design on your skin with washable marker and trace it over while doing the sewing.
That’s about all the info I can think of at the moment. If you have any other questions feel free to ask. There might be some things I didn’t cover.