used nylon on these, did not care about thermal expansion cause it's big piece so deburrs don't effect much. pla might cause trouble cause it will be tighter than nylon. try on 45 degrees, first it might be able to fit on the printer bed area, second don't trust the printer's build in angle, it's probably not a perfect 90 degrees, and will make the final piece tilt and causing trouble on milling stuff.