Method Two: Use Slotted Layout Joists
For all backdrop slots I was faced with making 1"-deep slots that were 1/8" wide, and my local hardware store informed me that there were no routers that would do that, so I should try a saw blade. After measuring the ones in the store and finding none that were right, I had to spring for a $40 dado blade set that would allow me to make deep grooves of 1/8" to ˝".
The idea was to make 1" slots in the joists and then press the one-sided or two-sided backdrops down into these slots. Ideally, that would mean 25"-tall hardboard to accommodate the full Walthers backdrops, but I was too cheap and went for 24" because the hardboard comes in 4' x 8' sheets and the layout needed 78 linear feet of the stuff (and I had no use for 78' of 23"-wide hardboard).
Slots perpendicular to the joists were all handled at once: I stacked the joists up (prior to assembling my benchwork), clamped them together, and drilled all my 3/8" bus wiring holes as well as sawing the groove with my power saw. Note: even though the dados are meant for table saws, I encountered no difficulty putting a dado on my power saw—I did have to reverse the blade washer because of the blade's thickness, however. See fig. 2.
Some of the slots that were needed were parallel to joists, so I could either saw a groove all the way down the board edge or use two parallel joists with 1/8" balsa wood spacers brad-nailed in 1" lower than the top of the joists. I chose the latter because I don't relish the face-fulls of sawdust that the dado blade bestowed upon me. See fig. 3.
Hardboard is stiff enough to work well as a backdrop support supported only by a 1"-high slot, so there was no problem there. I also used backdrops against walls, and these needed the balsa wood spacers as well, because the benchwork was screwed to the wall and there needed to be a way to get the backdrops to stay against the wall—one that didn't involve gluing them there, or mounting them on rather than against the edge of benchwork. I like—as this article suggests—removable backdrops, so I hesitate to glue them to walls. And backdrops on top of benchwork edges just take up space needlessly.