This lightweight “magic box” is an extremely affordable and versatile utility to help your magic show run more smoothly. While these exact boxes are harder to find now, the concepts and ideas are applicable to any type of prop box.
Where Ryan shows how he uses these folding cube boxes in his show, and introduces the "upgrade" that is the SKUBB box, and several ideas for organizing your props inside.
Dumps, steals, prop management, and even the option for advertising!
These are made with the SKUBB series of boxes from IKEA, which means they should be available worldwide! You can browse the SKUBB collection at IKEA to see what they have.
Update: Unfortunately, as of 2022, they no longer offer the large black boxes. At this moment they are available in white. I've tested several other folding boxes from IKEA and no others are built as sturdy as the SKUBB.
You may find similar closet-organizer or storage boxes that fold flat. However, I found these SKUBB boxes to be more durable than most, as they are made with a corrugated plastic inside rather than cardboard.