Materials: 20 threaded steel rods, various sizes. four 2′ x 2′ x 1/2″ oak plywood panels. Nuts and washers. Material cost: ~$100. Time spent: ~14 hours.
The rods become denser in the center where they’ll carry more weight.
The thing is solid as a rock. If i were to make another, I could probably get away with fewer rods, and thinner rods.
A fun little project.