I made a cold frame from an old sliding glass door. The 2 doors are only an inch different. So I built the frames the same size. My evil plan is to make 2 cold frames and 3 raised beds. All the same size. In a row with landscape fabric and pea gravel. I'll skirt the whole thing with 2 rows tall of 8 ft. long landscape timbers.
Here is the first frame with a tray of mixed tomatoes and peppers.
Here it is with a small ham added.