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Go to a farm and fleet store and look at the heavy tarps
I built one when I first started out. The best advice I can give anyone thinking about doing it is take the money you're going to spend on this and buy a hub. If you're committed to the idea the first tip I would give you is to revise your floor plan. The insulation sandwich is going to be overkill, expensive, and heavy. Plus I'd worry about moisture getting in there and rotting the whole works from the inside out. I'm assuming you're going to have it up on runners so you can slide it around and keep it from freezing in. If so you're going to have a cushion of air plus a sheet of plywood between your feet and the ice which is plenty sufficient. If need be you can always bank it in too. Heat rises, so it's completely pointless to have a heavy duty insulated floor with fabric walls.For the canvas finding anything thick or insulated in one big piece is probably going to be very tough or very expensive. You could use canvas drop cloths or try checking at local fabric stores but you will need to sew pieces together. You might find something that would work well at the type of places that make custom boat/car covers and awnings but be prepared $$$$.There isn't really a whole lot you can do to trick out the inside of them since there's virtually no space when it's folded. You could probably put a small rod rack on the side opposite the door and fold that side first. You can hang your jackets or whatever off the spreader bars if need be. If you want a cleaner looking setup you can buy catch covers for the holes, but you need an electric auger or you're gonna smoke the place out and spend all day smelling exhaust.I'm not sure what you mean by "semi-permanent" but I wouldn't feel comfortable leaving one of these out on the ice unattended, especially if you end up sticking a bunch of cash in nice canvas and stuff. First the elements will be tough, and it only takes about 60 seconds for two guys to fold one of these up and sling it into a truck bed. [/quoteonly using the insulation sandwich because i have that stuff laying around, the wood is all treated and will be doing a coating on the outside and using a couple old tubes of silicon around the outside to seal it better, and im honestly not worried about anybody stealing it because when i do leave it out for weeks at a time it would be on my uncles private lake and i literally almsot constantly have people who ask to use my hub style when i leave it up and that lasted my family about 10 years until it essentially blew apart this year, so im not scared of people stealing it