How to secure a glass?

I have this frame and it has a mirror glass that is not attached at all. There's no room / depth in the frame to even secure it with nails or anything. How should I secure it in place, preferably an easy method that's somewhat dignified and durable of course?

 

How about strong tape? I have done that in the same situation. Also brackets or large staples might anchor the glass at an angle if you gently push them in. Another trick is buying hardware store metal rectangular or oval pieces you can screw in at an angle over each corner of the glass on the back, these would be small thin metal bands with small screws.

 

I think this is what toomanytocount is referring to, and it was my first thought as well....

https://www.amazon.com/eBoot-Pieces...rd_wg=4OFNm&psc=1&refRID=Q3X7BPVYT6MSYPGRPY8N

Hardware stores carry these, so no need to get them from Amazon.
.

 

How about glazing points?

 

Exactly what I meant. These are good when building your own frames too.

 

DO NOT use tape, it may pull the coating off if removed! Glazing points are the best if carefully placed.

 

I had a frame that had its back covered in old duct tape and its glue and it wouldn't come off at all.

 

Turn buttons. They can be loosened to change the art work and they can be placed between corners.

 

Seconded. If all else fails, epoxy the sucker in if you never want it to move again.