If this is just an elevated blind,(?) I would recommend taking 4 4x4 posts as the main legs, bringing them up into the blind, bolted with a 2x8 rectangular floor frame. Then use 2x4s as the cross struts for the floor frame, with a 2x4 underneath the other 2x4s long-wise in 1 direction with the 2x8 (to add support so its not all held by 2 nails through the 2x8 lengthwise into the 2x4s. Then there will be a 2" gap between the 4x4s and frame outer edge once mounted (make the 4x4s go up 10-15" above the floor frame). Bolt it all together. Bolt a 2x2 or 2x4 rectangular frame about a foot off the ground. Create X-brackets on 3 sides and one cross brackets on the back end of the other side, with cross struts for a ladder on this last side. For the blind itself, attach 2x4s to the 4x4s resting on the 2x8 floor frame with one side 5-6" below the other (there will be a 2" overhang with the 4x4s if put in the corner-use this as the anchor support). Attach 2x4 or 2x2 studs on the roof rectangularly. It will appear wobbly without cross braces, but solid plywood walls will fix this easily. Cut out plywood to fit the walls, and have the roof in 2 pieces so that it will overhang by a few inches in each side (make sure roof has one side lower than the other!). The floor can be in 2 pieces of plywood, but cut out a 6x6 square at each end so that it will fit(therefore you can install it from inside the blind standing on the frame once erected). I've made a few of these before, both 4x4 blinds on 7.5 foot base and one 4x6 blind on 7.5 foot base. It isn't too complicated, but it will take a little planning and a decent deal of work and likely 2 people and a strong ladder. It will be heavy as hell, but it will also be a sturdy design. I like to overkill on the structure so you may decide to skip/alter a step or two, but make sure it is strong enough. I've used pressure treated wood so you don't have to worry about it rotting, but painting is ok if re-painted regularly in the field. Oh, and for the roof don't use shingles (because so heavy), instead opt for aluminum sheeting (the kind that ridges up and down, and oriented so that it makes sense for falling rain on the shorter end of the blind). Total cost including lumber should be in the ballpark of ~$400-500 and it'll last for many seasons. Just make sure to replace the plywood floor every few years, or anything not pressure treated if any water damage (cracks between walls if not calked). Its easy enough to draw out the plan for this, putting it together without it falling apart during assembly before getting the cross-braces and plywood attached (rectangles aren't strong unless there is an angle (triangle…) to keep it strong).