The shape of the dish is designed so that a mech's hollow base fits over the top of it, letting it stand fairly securely. It even works semi-reliably with models that have pegs protruding into the base like the reseen Wasp because there's some space inside the dish for them to fit.

This design is meant for SLA printers - the truss is quite thin. I printed the flat-base version straight onto a flexible plate with no supports. The "semihollow" variant is not tested and will definitely need to be supported.