I think ‘further refinement’ is kinda against 3D printing. Pla sucks to work with after the fact. Overheats and becomes mush. Lots of fdm filaments that would work. Abs,nylon,etc. what you have to remember is that 3D prints aren’t solid generally. If you need threads you use things like brass inserts that are melted in place. You can even pause prints to drop hardware in the middle of a part like if you want a captured nut. Also fdm parts aren’t uniformly strong due to the layers. For small stuff resin is more accurate and homogeneous. 50 micron is ‘rough’ for it so parts are pretty finished out of the gate. However most resins are brittle outside of a couple engineering resins. What are you hoping to make?