In my Lego Modulex collection, I have three different kinds of drawer housings:

1. Presumably more modern MDF-based drawers with round rubber feet (rare - orange in the pictures)
2. Presumably more modern MDF-based drawers with stripe-shaped rubber feet (far more common)
3. Plywood-based drawers which do not have feet

The advantage of the drawer housings with feet is that they also have recesses in the top so that when you stack them they lock together. Considering you're pulling the drawers out and pushing them back in, having them lock together helps a lot to keep them from sliding and tipping over.

This adapter attempts to solve that problem by locking around the edges of a plywood-based Modulex drawer and adding places for the feet to interlock. Also included are models of both types of feet.

Of note, one strange thing about the round-style drawer housings is that the feet are not placed on a rectangle. They're not even placed on a trapezoid. And the alignment of them on the top on bottom don't really match. This design reflects that by including all of the placements and reflections of them so the adapters can be used on either the top or bottom of a footless drawer housing and should still match up with an adjoining round-footed drawer housing. It's a little less of a positive interlock, but it seems to be adequate.