Visor mount

Looking for a little help, my son did a 3D printed visor for my HDS-12 Carbon. It fits great but I’m not sure how to mount it. It has the holes in it but I’m wondering if anyone else has dealt with this. The holes it aligns with are not threaded, they look like they go all the way through to the back of the faceplate and they’re shaped like a kettlebell weight. I posted this yesterday on the main forum and someone replied and suggested posting it here. Any answers would be greatly appreciated. Attachment 509362
Attachment 509363

Not sure if the same but look at Berley Pro and how they mount :dono

Lowrance Visors | BerleyPro

Maybe try and find some of the plastic interior trim plugs the same size. :dono