the 1/2"plywood base is 22x24". The dimensions are determined based on the space they will be used in .
I used these 1" plugs to anchor the pipe
The PVC is 1 1/4" basic schedule 40. The verticals are cut to 22"
The catch tray is a 18x26x3" pizza dough rising pan. I will set an Autopot XL tray in it. If I mess up the auto valve, hopefully the tray will catch most of it.
I will cut 2-3" lengths of 1 1/4 pipe to use as bushings for the top of the 4-ways. I will add a top frame made of 1" pvc. 1" pvc nests and slides nicely inside 1 1/4" pipe
This is one of similar size in use