OK, on second thought getting paint chips in my garden is a terrible idea. I assume it's ok to use translucent plastic sheeting to cover them at night.

I've used old window frames before..I scrape any loose paint from them, discard it, and use a new oil base paint to repaint the main wood and reputty spots if the putty is breaking off near the glass.

I just made a raised bed and put the window I picked up on it and found out that I lucked out; it fit as if I had measured both (NOt) two cheap hinges and a lid brace from the hardware store and it is fine. Oh, I did have to raise the sides and back to make an angle but that was easy with scrap plywood.