Using TEN 40x48 pallets (most common size), lay two on flat ground (best over 32 12x12 stepping stones) going 48 + 48 (eight feet). Across the back, wire (can use clothes hangers, #10 electric wire's easier/faster) two upright pallets 48 + 48 lengthwise. Wire two pallets on the top, 48 + 48. You now have a 40"-high frame with an open front. Wire one pallet to swing open and shut as a door. Put a piece of plexglass or clear plastic over the front of another swinging pallet on the front to be a window. Now BUY a couple of large tarps, I'd use camouflage color, and cover everything, stretching tightly, inside and out with it. Use screws and fender washers to attach the tarps for top, side, and door. Use one uncut piece of tarp for exterior and try for one uncut piece for the interior ceiling, walls, and floor, i.e., wrap it like a gift box. If you want it higher, wire two levels for 80 inches high, but that will require some 2x4's for bracing. If anyone wants to add to or change this description, please do, but keep it CHEAP!