If you wanna make your own, use a hole of 49.91mm for a tight fit, or 49.95 for a looser fit. This file is 49.91mm opening and has a tight fit on the monocular. It slides off without much force, has a rounded cap but there is still a ~30mm diameter flat circle the cap can rest on. I cooked it a 8.5s per layer, main thing to note with supports is to get a 4.90 mm connection length for the top support settings and 65% density, assuming a z lift of 5mm. I tried flipping the cap so it had a smooth outer shell, but the lens cap teeth wouldn’t form properly when I did it that way.
Download from thingiverse