Here are a few clever projects/designs made from plywood, here’s a ladder Link.
A computer desk and chair, all from one sheet – Link.
A puzzle chair (also from one sheet) – Link.
A really fun DIY chair (no glue or fasteners needed, the hammer is a soup can) – Link.
And last up, a little morbid – these flat coffins that also assemble quickly and without fasteners glue – Link.