Thanks for the mention of my article in PFM, Colleen. That project used a standard moulding with window mats and glass on both sides, and hangs on a wall. In order to see the back of the money, you have to take it off the wall.
Free-suspension of a back-to-back 2-frame assembly is more elaborate work, but not difficult. My only suggestion is to use optically coated, UV filtering acrylic on both sides instead of glass. The glass is a terrible insulator and would condense moisture readily, which probably would result in foxing, mildew, mold, or maybe other destructive nasties inside the frame.
The benefits of using optically coated acrylic are:
A) acrylic is a much better insulator, which would not readily condense moisture inside the frame, as glass would;
B) acrylic has half the weight and 20 times the shatter-resistance of glass;
C) optical coatings make the glazing almost invisible;
D) optical coatings reduce static charge to less than ordinary glass; and
E) optically coated acrylic is abrasion-resistance treated (OP-3-AR) before coatings are applied, so it would not scratch easily.
