These tweezers are made to be one-piece, because hinges and stuff need tolerances and tolerances make tweezers $#!tty. I have no tolerance for tweezers with tolerances. So here it is. Not as accurate as metal ones, but usable (unlike ones with tolerances, which are not).

Filament: I printed mine with titanium (just kidding. White filament usually contains titanium, but it's still plastic), I mean with PLA (how about we call it PLA-TD for titanium dust). I expect PETG to also work but due to it's higher flexibility it will probably be even less accurate. I may make a PETG version to compensate for that later.

Orientation: make sure both legs fully lay on the bed. If you have any overhangs whatsoever, it's not the right orientation and you will lose flexibility while having a more brittle tool. Lay those legs down on the bed, make sure you don't need any supports.

Perimeters/Walls: I used the default. If you play with and and get interesting results, leave a comment and I'll update it here. For example, I'd try to see if increasing them reduces the "wobble" and makes the tweezers more accurate.

Top/Bottom: probably there just for esthetic reasons. it's all walls for this model. Unless your orientation is wrong.

Infill: just like perimeters, I used the default. Concentric infill may be usable for reducing "wobble", but I guess if it does, then perimeters will do an even better job anyways.

Layer Height: I did 0.15 mm, but I think any layer height will work. The main functional implication I can think of is bigger gaps between layers which may change the tool's ability to grab tiny stuff like stringing. If you want to use them to clean up a model, perhaps do as small as possible.