My choice from these would be UHMW. Best machining of the group and at least
in my very limited experince doesn't seem to break down when used outside.

Use a VERY SHARP HSS cutter and a cold air gun if you have it or an air hose
if you don't. The problem here is melting on the cutter, so slow the rpm's
down if you get that. All plastics don't hold their shape well, UHMW is no
exception, light cutting and clamping forces help. Also water can absorb and
change dimensions on UHMW, I think.

My knowledge here ain't perfect. Maybe others would care to comment.

Karl