Ron Newman’s fantastic page on DIY room-temperature anodizing of aluminum parts was last revised in 2007, and looks like it may be significantly older than that. Ron’s selling a how-to book, now, and a bunch of anodizing supplies, from the same page, but to me it looks like there’s more than enough free info there already for a savvy person to figure it out for him- or herself. And while Ron’s set-up, pictured above, may look intimidating, it’s actually possible to do this without a lot of expensive equipment.
Can you only anodize aluminium in a sulfuric acid bath? I looked into this a while back, and sulfuric acid is really hard to find here in Australia (can’t even get battery acid from auto parts suppliers anymore).
I was also reluctant to keep containers of the acid lying around in my garage.