Structure
The construction technique is basically like making kitchen cabinets. Mostly 3/4″ Home Depot plywood and some MDF. Also, built like a brick out-house. Sturdy. Climb in, climb out, using the side footholds as aggressively as you want.
Woodworking is glued and screwed, and made up of four independent modules that are bolted together. That allows for disassembly. Each module can easily make it through a doorway, so the rig is not permanently stuck in the room.