To give you a place to start, there are two general kinds of sex toy adaptations. There is the kind where you take a toy and change some aspect of it. You can build up a handle, change the switch, or attach the toy to something else that lets you use it. The other kind of adaptation is where you find a toy that may be intended for an entirely different purpose, but actually suits your needs.
Homemade adaptations (using grab bars, reachers, foam, tape, gloves, etc.) can be a great way to adapt a toy, and you dont need to wait for an OT! If you stick to inexpensive toys, the adaptations will probably outlast the toy.
On the other hand, finding a toy that doesnt need to be adapted at all can be good. For that you mostly need to be creative. A good example of this kind of adaptation is really long sex toys. At first you might think buying a vibrator thats 14 inches long would be ridiculous. But if youre someone who needs to get a complete firm grasp on a toy, and you have big hands, then your hand ends up covering most of the toy. You need those extra 5 inches just to get a good grip. There are other toys that are made as rings to wear around the penis, but work really well when strapped to hands and fingers. And then there are a thousand things you can do with remote control toys.
The benefit of not making a major adaptation to a toy is that you dont usually need to rely on someone else to adapt it, it doesnt cost you anything, and you only need to worry about the toy breaking, not the adaptation.