For a cage probably .060 or .080 round rod. I just did a cage in .080 and it was my first time and it turned out pretty good after some trial and error. Scales out to 2" tubing. I am getting into scratch building more and most of the items you will need are based on what you are trying to accomplish. Reference photos, a caliper, super glue, plastic welder (ambroid, tenax) and a miter box with a saw is a good place to start IMO. The plastic, aluminum, brass, etc. are the easy items.