Google Zoeller forge-it is one place to get supplies, but there are a lot of possibilities. Check if you have a pottery supply place nearby-they'll likely have Kaowool and ITC 100. As for design, you can do a search on here and see some good pics of Karl Anderson's forges to get a good idea. You can use a needle valve for the gas instead of a MIG tip, it just depends on the design you go with. Search the internet and you'll find a bunch of different models and styles. Forced air can actually be simpler to build than a venturi style burner.
Jeremy