GardenGoober said:Same problem here. I really want to buy one of those automatic vent openers but having a difficult time finding one that will lift the shower door ... unless I pay $140. 
I thought that I would try to build some material into the top of a cold frame that I could easily cut slots into. Cut out around 40% of the material in a series of slots.
Then lay some more of that material over the cut-out area, supported by some groove or track running horizontally so the extra piece could slide back and forth with only friction, no weight.
Then cut out 40% of that material, in slots the same shape as the slots in the wall or roof.
Then arrange the "vent opener" to slide the second piece sideways to either open it up by 40% (align the cut-out-slots) or close it 100% (mis-align the slots).
Does that make any sense, or should I try to sketch it?
