Brackets are fixed to the drawer front and back with 10mm 6g countersunk woodscrews and a suitably sized 6mm threaded rod (print brackets have 6mm thread designed in). The threaded hole is offset to allow it closer to the drawer bottom to also reduce sag when too much heavy stuff is stored.

I used PETG rather than PLA for additional toughness and strength. On my 15yr old drawers I had to pull in about 8 mm of bow in the drawer back piece