More in Kitchen
Nail the shelving into the box, spacing the bottom three shelves just far enough apart to fit baskets with a 1x8 board below them.
Cut a piece of shallow plywood material to fit the back of the shelving unit. Use construction adhesive to secure it to the back of the shelving unit and nail it into place.
The shallowest drawer runners available are 12 inches in length. If your shelving unit is shallower than that depth, use a reciprocating saw to cut the middle section out of each runner, keeping the back and the front of them.
Using a chop saw, cut a 1x8 board to the width of your shelving unit to create a shelf base for each basket.
Screw the drawer runners to the shelf base. The front half of the drawer runner will sit flush with the front of the drawer base, and the back half of the runner will butt up against it, overextending the back by about an inch.
Attach the shelf base to the bottom of the basket using construction adhesive and two or three 1/2-inch screws. The back of the basket should overhang the back of the shelf base by about 1/2 inch. The front of the basket will overextend the shelf base and the shelving unit itself by a few inches.
Screw the other half of the drawer runners onto the inside of the shelving unit. These should sit directly on the bottom three shelves, and the front half should sit flush with the front of the shelving unit with the back half butting up against it.