Ikea used to make these boxes that were made out of 1/4" plywood connected with 8 galvanized metal brackets that had an extra lip on the top that helped keep the box together.
I wanted to use the same method for making some boxes but I can't seem to find these kinds of brackets (pictured) anywhere. I may be using the wrong keyword to search. I've tried box corner brackets with multiple variations to no avail. I've only found ones that don't have the lip at the top that grip the plywood. The ones I've found only seem cosmetic and not structural.
Does anyone know where one could find brackets like these mass produced? I have asked local metal fabrication companies but they all say it would cost a lot to make custom ($30 a piece) I would need 8 that have a 1/4" lip that can grip the panels of the box into place.