Cold frame

I acquired a number of secondary glazing windows which could be leant against each other to make a ^ shaped cloche. To stop them sliding apart we cut notches into some lengths of wood to place under the glass, at right angles to it. In other words, 2 notches in each plank, that both panes would drop into to make the triangle. They were the clipped together at the top with some giant "bulldog" style clips made from pieces of bent metal.
It worked well as a cloche/cold frame and could be dismantled and moved easily. The downside was the glass panes were heavy as they came from large windows.

If I did it again I'd use smaller windows or polycarb panels.