Fixing broken/missing screw bosses on plastic parts

I've got some of the screws so I should able to figure out the length easy enough. I think I can glue them in and the run through the housing to keep them straight.

Grease should a great mold release- or car wax.

I'm a plastics engineer by trade- I can get lots of ABS runners from the parts we mold! I think the lenses are actually acrylic. If they were polycarbonate, they would have turned yellow from the sun over time