I created this box using 6mm plywood. At the time I didn’t had a table saw, nor any workshop, so I asked nicely in the hardware shop (OBI) to cut the pieces.
I glued the sides and the bottom together and made sure, it’s square. I added the top using a piano hinge and a support to avoid crashed fingers. I glued a big Lego plate on the top with 5 minutes Epoxy.
Although I didn’t use anything else than glue, the box is strong enough to hold a person sitting on the top.
I painted with kid safe paint using more than one color for the fun.
Because of using multiple colors, I couldn’t paint every site at the same time. Building the project was maybe an hour, then I waited for the glue to dry, then the paint job. From buying the materials to finishing the project I needed no more than 2 days.