With three pairs of these type of magnifiers, I found I needed to hang them somewhere instead of laying on my desk. This is a new version that assembles with (2) 3mm bolts 8mm long. You can also use screws. No need to glue. You can assemble them by locating the front to the back using the slotted groove to locate the correct position. No need for inserts as the bolts/screws will easily grab into the plastic.

Note: The orientation of the parts is critical. The back plate should have the slot (or smiley face) on top, otherwise any elephant foot will close up the slot and make it difficult to assemble. The front part must be oriented so that no supports are needed. The bolt supports are tapered to eliminate supports.

I have printed multiple of these in various materials but PLA will be fine. They were printed on a Prusa XL (6mm hotend), at .25 layer height, no support.
Happy printing.