What kind of coating is being used on the aluminum frames

[petercohen]

The aluminum frames on the DARwIn-OP look quite nice. Anybody knows how to make those frames?

[Bullit]

I believe they are simply grey anodized aluminum. I'm not sure what aluminum ROBOTIS is using. Historically they used 6061 but I find 6061 challenging to bend. 5052 is much tougher just a little harder to cut. Most people don't anodize themselves. Once your parts are cut and bent send them out to be anodized. One of the things ROBOTIS does on the Darwin brackets to keep the bends tight and that is a little different, is that they use 2mm material and at the bends they mill it down to 1.5mm.

All of the Darwin mechanicals are available online Darwin-OP physical information