To attach the backplate to the wood I used threaded inserts, 4-40 machine screws, and my trusted friend with drill bits, Kina. The inserts are hammered into a hole in the wood, and contain screw threads on the inside so that the screw can be loosened and tightened over and over again without stripping the screw. I was a bit weary about using them at first, but they turned out to be an absolute necessity!
Kina taught me a trick to make the hole the perfect depth — measure the exact depth with calipers, then place a piece of tape on the drill bit at that location. Then, you have a visual, consistent cue to let you know how deep to drill! Genius!
First we drilled holes the width of the screw into the plastic. Then, we needed to counter sync the screws into the acrylic so that the acrylic could lay flush on the wall. The counter sync drill bit did a great job but we had to go very slowly so that the acrylic didn’t crack. A quick pre-drill for the picture-holder nails and all the pieces were in place!