CornerCaddy

This is a CornerCaddy. You need 4 of them to complete a table/bench. It is designed so that you place a 1.5" PVC pipe in the bottom (elongated hole) and a ¾" thick sheet of plywood in the slot. These CornerCaddy's will go on each corner of the wood sheet and create a table/bench. You will notice that the top is open as well, this is so you can insert another PVC pipe on the top side and create a shelving unit should you choose. I recommend a minimum of 5 walls and 5 top and bottom layers along with 35% infill - I use Support Cubic for mine. Designed for using PETG, though I suspect PLA/ABS/ASA/etc.. will work just fine. My calculations say it should hold 200lbs if using  a 2 foot by 4 foot MDF/Plywood top. Be sure to support your PVC by adding braces for stability (t-fittings and cross pipes should suffice).

As with anything, you do this at your own risk. I've tested it for MY application and found it acceptable. You should absolutely test and proceed with caution.