I honestly do not know the difference between and a stim toy and I usually use the two terms interchangeably.
My favorite fidget toys is my flippy chain. I use this thing all the time and take it with me everywhere. And I love that it’s discreet and quiet.
What’s your favorite fidget toy, or thing yiu like to fidget/stim with?
It’s really easy to add holes. One way is to just pop the shape you want into TinkerCAD, export as an STL, import into your project, add the part to your model as an assembly, toggle the shape type to a negative part, then position it where you want it. Then slice the plate, find the layer where you want to insert the weight, and right-click to add a pause. Then pop it into the hole and resume the print
Okay, yeah… I guess that is a lot of steps, now that I see it written out. But none of those steps are hard, lol. Takes like 5 minutes, once you’ve done it a couple of times.
I often put 4.1mm by 1.6mm cylinder holes into tiny prints to add 4×1.5mm magnets. If you want to add bearings for weight, I’d suggest trying a cylinder hole so it slides in easily. (I haven’t tried it myself, but it makes sense in my brain that way).
I’m not sure the best way to keep it from sliding around in there, if your tolerances aren’t right. Maybe put some glue in at the same time? If you leave it paused for a couple of minutes, I imagine the bed heat would dry the glue quickly, so it shouldn’t ruin your print with moisture, I wouldn’t think.