Here is a site with pictures of a DIY bio user...

http://www.kelseyville.com/biodsl/

I use used oil from Checkers Drive in and a local fish house. The old nasty stuff in the grease dumpsters out back. I get this for free, mix with a 15-20% mix of pure methanol and Red Devil Lye. End product is bio-diesel, and liquid soap. Filter the bio off and into the tank it goes. Car loves the stuff. Runs with less clatter, no smoke, and smells like french fries
Trade off is about 3% less mileage per gallon,and as mentioned above more fuel filters. This stuff will clean out 20 years of junk in your tank and it will gell at low temps if you do not use full 20% methanol when making it.