[DonRotolo]

I second the interlocking tabs.

My father (nor 92) owned a company that did die-cutting of cardboard. Back then, it was all hand-cut, but some of those dies are amazing.

For those unfamiliar, you first cut a thin line through plywood, then fill the space with a strip of razor steel "rule". Squish the finished die onto a piece of cardboard, and viola', you get cutouts. Think jigsaw puzzle. They used to get something like $10 an inch, decades ago. A typical 22 x 34 die might have 1000 inches of rule...

Consider using thin plywood with a fiberglass/epoxy coating where strength and low weight are a consideration. Do the math correctly, and wood can be pocketed like metal for weight savings without strength loss.