A couple months ago I bought a few AT2020's on sale for $79 each to use as a platform for a stereo ribbon mic that I'm still working on. In the meanwhile I had a couple of the AT boards and capsules sitting around collecting dust, so I decided to see what I had lying around in my supplies where I could slap together a microphone out of leftovers. Ingredients: one aluminum tube, some copper water pipe, some brass rods, stainless filter cloth and scrap acrylic. But since I was about to spend a decent amount of time machining stuff, I figured I'd kick in a few dollars for the larger electret capsules that Kingkorg suggested. I'm glad I did, they sound much better than the stock 2020 capsules. So I guess the only part of the mic that is still an AT2020 is the circuit.