This is a very basic DIY, home-made, cheap, foldable setup that I use for product photography - mainly for my gear and anything interesting that is about a foot long or smaller in size. All I have here is:

4 sheets of polystyrene foam - commonly known as thermocol, or styrofoam (which actually is a Dow Chemical trademark) - making top, back, left and right walls

The left/right walls have a large window of foam cut out, and a silver/white sheet of paper pasted to fill the window

I simply use long pushpins to assemble the box on the fly. when folded, its just 4 sheets of foam

some regular paper sheets (white / blue / black) for use as a backdrop. I just pin the sheet on back wall and let it flow to the bottom without any hard fold showing up

A vivitar 285HV and canon 430EX flashes illuminate the side windows using wireless radio triggers. I usually shoot the flashes in manual mode, adjusting the output and distance from the box based on lighting needs