This cover set for FEP vats is designed to stack securely enough that you can move multiple filled vats without risking spills. Base is designed to retain resin in case of a slow leak and supports the vat by the edges so the FEP doesn't get a dent in it from debris. Cover forms a light baffle which should be effective in keeping out stray light if spray painted matte black. I add a sheet of shop towel to the inside of the cover to cut down on resin drying out.
Should not need support printed in orientation given but will likely need a heated bed to prevent the lid from warping if printed flat.