6061 - t6 is the cheap run of the mill aluminum alloy with a neat sounding name. I'm a machinist and thats what my customers spec for cheap disposable parts. Check with "Metal Supermarkets" they are franchised around the country and usually have a good selection or look in the yellow pages and call a local aluminum supplier. Ask for the order desk and start asking questions about alloys, they'll help or get you to someone who can tell you what a good alloy is and then ask where to get what you want.