Modifying an old base cabinet

If it would fall apart when you try to level it, how is it going to support drawers?

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

1/2” slope which way?

First thing I would do is check the box for square – side square to the front. The sides need to be parallel or you’ll have big problems. To correct you shim the slides.

The drawers need to be level side to side and front to back. If you try to adapt the slides to the cabinet, you’re heading for problems.

Are the drawer fronts inset or overlay? You can fudge the drawer fronts to make things look right, overlay fronts are the easiest to do.

Why do you need to make the opening larger? Make a filler strip for the slides to mount on that flush with the face frame.

-- Everything is a prototype thats why its one of a kind!!

The cabinet is square. The slope is the floor it is anchor to. The opening I plan to make larger is the height because of the need to put a face piece across to separate the two drawers. Inside the cabinet I plan to use plywood on each side to make it flush to the front. You recommend making drawers level front to back and side to side. The drawers will be overlay.