ive made a couple. on one i used 1/4" steel box tubing which worked best, and the other i used galvanized conduit which is very heavy. both work good, just be sure to weld them good and dont skip anything to save time. like max said, use something for teeth to dig in to the tree or they will slide a bit, especially in the rain as i've learned...thats not good, i never fell but almost have. for the floor try to find some of that steel grating, it works great. i dont have any plans or pictures, i just did it as i went. be sure to use rustoleum paint or they rust really fast. good luck