I build my own elevated box blinds. In the past 4 seasons my hunting buddies and I have put up 16 of these. They are either 4'x4' or 4' x 5' - 6'6" inside height. The 4'x5' design is substantially expensive mainly because I have yet to figured out how to avoid rather substantial waste. I put them on either an 8' or 10' platform using 4x4's fr the leg posts. I tried 4x6's, but did not notice any substantial increase in stiffness. All framing lumber I use is treated pine. Sides are 4-ply 17/32 deck grade plywood. The roof is tin. I use deck screws rather than nails. I paint the inside with the cheapest exterior deck stain I can fine, and the darkest near black that I can get. On the outside, I use good quality, flat latex exterior paint in cammo colors.

I just built 2 - 4x5's, 10' platform. My design is stout. These ran me $325 +/- each. The 4x4 runs about $260 each.

My hunting buddy has bought two pre-made woodframe box blinds .... similar to my 4x4 design. It is adequate, but much cheaper made and not painted. Sits about 5' off the ground. He paid $350 ea.

I have tried OSB in the past, but decking plywood outlasts it by leaps and bounds as long as you keep it painted ... about an every 5 year task.

Any one want more details or a plan "sketch", just let me know. I'll be glad to share.