I used H-channel like for trellisses, to build a wooden frame around the heavy shower doors I found. The longest are 73 inches. I put brackets on the corners to stabilize them.
Two of the glass doors were the exact size of some wooden screen doors I had been using for cold frames last winter. I didn't have washers so I used woodchuck and beer caps temporarily.

Make for today: frames for curb harvested shower doors.

These will become a cold frame for the sunny front of my house.