I've had a lot of other projects so I'm late doing this. But it's time to replace the elevated blind I have. I know "what" I want, I"m trying to decide how to build it. Basically I want an octagon, with (roughly) 48" front and back, and 24" corners. That should give me roughly a 7'x5.5' floor. This will be going on a platform made of square tubing.

The question is do I use a flat platform and build up with wood? The current blind is built this way, with split 2x4's for studs. That blind is in bad shape and will come down by pushing the wood top structure off the platform.
The other option is to weld the framework for the structure to the platform, and then skin with insulated board or just plywood.

Either way the platform will be taken as a piece, and then the walls of the blind attached in the field.

My goal for this is to try to have it sealed well against insects and water. I'm already planning to buy the door and windows that are the RV style that seal well. I'm ok with either fabrication technique, I have all the tools to do either. I'm just wondering which might work better, and which way folks that have done it before would recommend.

Thanks in advance.

OK, let me ask a different question:

Which method of construction (metal frame with plywood skin, or wood frame with plywood skin) is easier to seal well against insects?

had a friend build a portable blind that he could carry in his 1/2 ton chevy truck in 6 pieces that would bolt together with a 2 person assembly (weight) on top of a pre-existing 5x5 elevated platform. He used 2x2 framing with 3/8 plywood (painted) for the 4 walls, 2x2 roof framing with corrugated sheet metal for the roof and 2x4 framed floor with 3/4 plywood. He stacked it in his truck in reverse order so when they got to their lease, it was easier to handling in order of set up. He used 3" lag screws from the inside to secure the pieces together using caulk between the pieces to get a tight seal. He said it was only a couple of hours to get it set up and fully assembled and the toughest part was getting the pieces from the truck up to the top of the existing platform. I think it was just a 4x4 blind and relatively short since they had to lift the roof up as the last piece. When he moved, he disassembled and took it with him to Mississippi and set it back up there.

All my blinds are like this. I want to be able to put it up myself if I have to.