Not my original work--downloaded from https://thangs.com/designer/Neigh/3d-model/Gridfinity%20Baseplate%20for%20IKEA%20Helmer-61866. Original design by Neigh.

The baseplate fits snugly into the drawer and I found I didn't need to use the alignment holes in addition to the magnets to keep it in place. I only wish the original design had spots for magnets for the bins as well. Printed on a Bambu P1S at 0.2mm with 2 wall loops and 15% grid infill.