Shadowbox tutorial
why not float it and shadowbox it in a square frame?
Is your item paper or does it have some depth to it? If it's paper, you could just mount it to the top of the matboard and use spacers to keep the glass off it.
SHADOWBOX (duh duh duuuuuhhhh!!![scary music])
If your item has some depth, ie canvas or tile etcetera, you will mount it to the matboard using screws through the matboard or some other sturdy, reliable method.
Use a very deep frame, at least 1 1/2 inches deep.
Create space for the item by cutting strips of matboard and strips of 1/8 inch thick foamcore. Allow at least 3/8 for glass and backing and the rest of the frame depth can be the width of you foam and mat spacers.
Clean glass, lay it in frame, using both tape (for short term) and glue (for long term adhesion) line sides of frame with foam, then matboard.
Some people like to adhere foam and mat first, then apply, but I find I get better looking corners if I do them seperately.
GOOD LUCK! HAVE FUN: this can be one of the funnest methods of framing if you are a process oriented person.