i actually figured out a way to sew a slip-on cover for the awkwardly shaped tray:
take the tray, and trace it, leaving about 1n inch between the tray and the edge of the fabric on all sides, then, without cutting, you move the tray beside your existing pattern, about 2 inches away from the line on the side that will 'fold over' (the fold will be the end/back of the tray pillowcase, whether this is the long or short side is entirely up to you
). then trace the tray again, this time leaving 2 inches between the other three sides of the tray and the line. cut out the pattern except for the line that marks where it will fold. it's a good idea to keep the line on the outside when you fold it as you'll be turning it inside out later anyway and the line is a good reference. fold the fabric on the line and
pin it in place - pinning is what will keep everything straight and therefore save you from a bunchy nightmare after it's sewn. then line up the remaining three sides (there should be lots of slack in the 'top' side) and pin them as well. sew going towards the folded side, 1/4 inch away from the edge on the sides perpendicular to the fold. about an inch from the edge, pull the extra fabric so that the corner lies as evenly as possible despite the excess fabric and try to stagger the inevitable bunching as you round off the corner. repeat on the other side, and of course there is no need to sew the folded side. turn it inside out, slip it on the tray with the smaller side on the bottom, and put it back in the cage for the munchkins to enjoy
i'm still working on an easy slip on cover design for the shelf .. i love the flexibility of ladder placement and the hooks but it's a pain to try to cover without using a million clips to keep my guys from pulling it up :wallbang: