I'm really not much of a DIY kind of dude, but I've been wanting a full-sized Olympic platform here at Styrka for a while. Problem is, commercial platforms are absurdly expensive — the smaller low end ones start around $1500, and quickly climb to two or three times that price. Most of that cost is due to the cost of shipping something so large and heavy.
Fortunately, it's not exactly nuclear physics to build a platform out of plywood and stall mats. I'll be using cheap(ish) pine plywood for the base, and then a nice piece of oak for the actual platform. The sides will be 2' wide, 3/4" rubber mats which are available for cheap at tractor supply stores. I'll finish the platform with marine lacquer just to protect the wood from sweat and spills, and a steel frame from Rogue will give it a finished, professional look.
At least, that's the plan. I've never done this before! But, as Christopher Walken once said, "If you want to learn how to build a house, build a house. Don't ask anybody, just build a house."