Relatively straight forward process, but aluminium only. From memory sulfuric acid and a 12 volt charger. The web is full of detailed instructions. I have a heap of anodised parts from a car resto I'm doing. They are pretty old and warn, so my plan is to un-anodise the parts, repair and polish, then anodise again. To un-anodise it's just a matter of hanging the parts in a caustic solution. Get's it back to soft aluminium again. This is where I'm at.