I'm kind of a blender noob and need some help. The picture below sort of sums up the problem. I have a pair of black glasses which I did not model. I also have some "lens models" that are 8cm in diameter and modeled to the exact shape of a specific eyeglasses prescription.

The image below is an exaggerated solution, some of the prescription lenses are a bit thicker than the frames, but not this much.

The obvious solution was to select a loop of vertices on the glasses and extrude them out into a mesh I can boolen with the prescription lens to cut it to size. This didn't work because selecting loops on these glasses didn't seem to work. So how to do it?

The prescription lenses are actually like real glasses lenses, I have to use them to get correct refraction when this is ray/path traced, so I need a way to cut them to fit the frames.

The model for these glasses is available here. It already has some lenses in the frames but not all models I want to use do, some are empty.


enter image description here

  • 1
    $\begingroup$ You say that "selecting loops on these glasses didn't seem to work", maybe you should share your file so that we can try, you should be able to select the frame and use it as boolean object $\endgroup$
    – moonboots
    Jun 15, 2023 at 20:19
  • $\begingroup$ Hi, at the very end of my post there is a link to the model on sketchfab. I have tried other models too and have the same problem with all of them. By the way, the way I got the white shape above was by extruding one of the lenses in the glasses. Doesn't work for everything though because some eyeglasses models have no lenses or have ones with odd topology. I'm still a blender noob so maybe I'm not doing it right. $\endgroup$ Jun 15, 2023 at 21:29
  • $\begingroup$ If it's a copyright free model, could you please share it on blend-exchange.com or another platform? $\endgroup$
    – moonboots
    Jun 15, 2023 at 21:31
  • $\begingroup$ The model is ccattribution. Are you unable to download it from the sketchfab link? $\endgroup$ Jun 15, 2023 at 21:33
  • $\begingroup$ Yes I need to register, if it's creative commons please share it $\endgroup$
    – moonboots
    Jun 15, 2023 at 21:39

1 Answer 1


If you select all in Edit mode and press AltJ it will untriangulate the frame and you'll be able to select the edge loop of the frame, then use it as a boolean object.


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