Bob
Here's one I have been kicking around in my head for a long time,,
Take some 3/4" plywood and put in 3/4" wide dado slots on 2" centers from one end to the other ,1/2" deep on the 4ft x 8ft ,then rip it into two parts,this will give you a left and a right side to a new corner cabinet,then take some pine or poplar and make a face frame for the front and some 1/4" plywood for the back, then cut some 3/4" plywood up for the side in shelves, because the 3/4" plywood is not 3/4" thick they will just slide in free.
A pocket screws to hold the front face frame in place and a dado on the sides to hold the plywood in place.
Drill in one or two finger holes in the slide in shelves so you can pull them pull them out all the way and so you can make the opening bigger by just removing it and store it.
Bj