Two new shapes for the Drawer tab, drawn to scale on a 42 mm grid with a 256 mm bed. Drag the sliders: the baseplate, tile seams and auto-filled bins update the way the real layout would.
The drawer is still a rectangle, with one or more cut-outs taken from it. Cells that touch a cut-out get no baseplate, tiles stop there, and bins can't be placed on them. Every other part of the pipeline (split, keys, packing) works as it does now.
Or drag a cut-out in the top view. Bins already on it are pushed off or flagged.
Front and back widths differ. Cells crossed by the slanted wall are either left empty (simple and reliable), or cut to the wall: the baseplate and a one-cell edge bin are trimmed along the angle. Cutting them needs new geometry and test prints, so it would come later.
Cut pieces under 25 % of a cell are left empty: too small to hold.