Do you want it off the ground a certain height? If so look for some solid leg braces. I use the metal racks like you see in Warehouse stores that are 6-10 feet high. Build my box say 6x6 and put a leg brace in alternating corners. Bolt the legs to the stand with LONG lag bolts. Make sure the floor has plenty of support. I use 2x6 or 2x8 or ect.... because that is the only thing that will keep you off the ground. Over the top of the floor supports I use a black mat for horse stalls so I never have to deal with carpet. Here are my dimensions for the last stand built:
6 ft wide square ( 6x6x6x6), 7ft high roof sloping to 6'6" on one side AWAY from the door. Framed in 2x4 in all 4 corners with 2 cross braced 2x4 running the lenght of the side wall. Use the cuts from the corner 2x4 to act as vertical braces within the wall. I cover the entire box in tin ( old barn tin or a dull color) and then insulate it on the inside. I attach the insalation with liquid nails and use the stuff that house builds use before they brick the house. it comes in 4x8 sheets and I cut it to fit.
I hope this is what you were looking for. I do suggest that you sit down and draw you some plans first and be very detailed so you do not get lost while you are building.
If it sounds complicated it really is not just get started.
-------------------- Big ones line-up, little ones bunch-up