Gatorbuck, welcome to the board! You will probably, like most of us, build a few boxstands before you get it down to an art that you like! Here are a few hints:
1. Most of them are built on 8 to 10 ft. legs.
2. You will want to buld the box itself, tall enough that you can stand up and stretch when you need too.
3. Some build windows all the way across each side, but really they don't need to be more than 20 to 24 inches wide and just high enough to get a scoped gun through comfortably. The larger the windows, the easier it will be for deer to spot you!
4. Also the bottom of the window should be high enough off the floor so that you will not easily be seen, but not too high that it would be uncomfortable to shoot from!
5. As for the side widths, 4'X 4' should be good for one person, 6'X 4' for two people. I once thought I'd like a wider stand, but after hunting from one, I found that I tend to move more and do not have as good of a view from the wider stands!
6. After building a sturdy platform,(I use landscape timbers and light wood for bracing.) Use a thick plywood for the floor, (I use 3/4" plywood.)
7. I use 2X2's for framing. It will feel kind of weak, but trust me once the siding is on and it is bolted together in the corners and anchored to the floor it will be just as strong as 2X4 framing, just a lots lighter.
8. As for the siding, 1/4 plywood (a good one is Luan Flooring Underlay) is as good, and will last as long as the thicker stuff!
9. Be sure to slant the roof a little and leave a few inches of overhang on the sides and it will stay dry!
10. After building a few stands, now I bolt and screw everything together. About 3 or 4 screws in each corner and 3 or 4 lag bolts in each side into the floor will make this stand as strong as it will ever need to be!
Within about an hour two people can completly assemble or disassemble these stands! Good luck!