What it appears to be is a polished aluminum frame that was clear coated, could have been lacquer, powder coat, urethane, etc. I would be sure to strip it completely before refinishing, what is on there is delaminating and simply covering it with a new finish will result in problems sometime later. I would use a stronger stripper, bead blast, or a lot of hand/finger sanding work to remove all of it.

It may or may not be cheaper DIY, depends if it's done correct and what you are after. There is no doubt it would be easier to have a specialist refinish the frame.