Make sure the glass is "replacable". Some frames have the glass "glued in place" and it's not easibly removed from the frame. Make sure you can remove the glass. (Note that some Amazon-branded frames are like this. The glass can be removed, but may break!)
What do you do with the glass from the frame? We have found that it often fits behind the arwtork, before you install the back panel of the frame. It's a great eco-friendly way to save and store the glass. Placing the glass behind the art adds weight to the frame and can even make the frame sturdier by adding a bit of structural integrity! And, of course, you always have the original glass if you ever want to repurpose the frame later!
For larger frames (11x14), it's not uncommon for the Clear ShadowBox's plastic sides to "bow in" a bit. Simply use "fillet tape", which is an extra-sticky double-sided tape, to keep the sides of a Clear ShadowBox snugly in place for larger frames. Place the fillet tape, double-sided tape, or even "spot dot" adhesive as needed inside the lip of the frame before inserting the Clear ShadowBox. A little bit does the trick to keep the long sides snugly in place.
If you would like the Clear ShadowBox to extrude from the opening of the matting, make sure the matting is cut to size by your local framing shop or get our pre-sized matting. Standard store-sold mattings are cut with an opening that's slightly smaller than needed for a Clear ShadowBox. If you want to make your own matting or cut an exisitng matting, cut the opening to 1/2" smaller than the frame picture size. For example, for a 5x7 photo in an 8x10 frame, make the matting opening 4 1/2 x 6 1/2