I just made a shelf like that myself on the 3D printer. I made mine with a holder for my battery that runs my lights. I may have to cut the slot for the skimmer in mine, I like that idea.
Brian, I see taking it one step farther by adding an extending piece to each end of your tapered bottom part to help the tray setting level across its width. Let the tray as it sets down on the 2 poles also rest against the laterialy. Clear as black mud?
I get what your saying. I tried it by just clamping the piece your mentioning on to what I’ve got when I built it. But with how tight the tolerance is where the poles are it didn’t seem to add much more support. That’s why the plywood is thicker so it doesn’t tilt down.