Hi Damon!
I almost exclusively got all of these parts at the hardware store, in my case Orchard Supply and Home Depot (California, though I think at least Home Depot is a nationwide brand). I’m pretty sure you can find all of these in your local hardware store as well.
The brass tubing I also got from Orchard Supply, though I think my local Home Depot did not carry those. K&S Precision Metals is the company that made the ones I bought (http://www.ksmetals.com/26.html), maybe that helps when you google for them.
Hobbylinc also has a good variety of this brand, especially the square ones which lend themselves nicely to armature building, but which can be hard to come by in the correct sizes to nestle them together like those Russian nestling dolls: http://www.hobbylinc.com/hobby-and-craft-metal-tubing
I hope that helps, but if you have furhter questions, don’t hesitate to ask! 🙂
Lisa
