well, in my experience there's some special glue that's sold at craft places. This glue is used for women's dresses, but you can easily use it for stuff like this. if you pull at it at a right angle, it comes off, something like that. as far as making the glasses, if you have access to a 3D printer, I'd suggest using that to print out the frames and then use hot glue or something like that (not a professional here) to fix the cut-down lenses from $5 sunglasses to the frames.
How did you do the glasses? I'm considering Jensen as a possible cosplay. I need prescription lenses but might look to getting scrip sunglasses and taking out the lenses (or ordering just the lenses) and putting them in the custom frames... spirit glues, I assume?
Yea, I just took the glasses out of ordinary shades and modeled the frame right around it with modeling clay. if you let it dry afterwards you can remove and slide back the glasses into the frame even without glue.