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The basic mechanism I used is a two-arm (four-bar) lever arrangement. Using two arms gives you the ability to raise a prop relatively straight up, avoiding an arc. This is a very handy design for pop-ups. Its used everywhere!
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Changing the length of either arm relative to the other dramatically changes the angle of the prop on the end. The drawing above shows a longer top arm.
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This shows the top arm a bit shorter than the bottom arm. This is the idea I worked with.
The Body
The body at the end of the arms can be built out of any lightweight material. I used PVC pipe. Here is the two designs I used.
Bottom Pivots
What's not shown very well is the body is made of 1/2" PVC pipe, and the lever arms are made of 3/4" PVC. The 'pivots' are places where the 1/2" pipe slips through the 3/4" pipe, making a simple pivot point.
Top Pivots
Whats different in the top pivots is that the body is 1/2" PVC, and the arms are slightly smaller 1/2" CPVC (note the "C" in CPVC). The CPVC easily slips into PVC fittings of the same size.... really!.
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A two-legged version worked great, but I wanted to reduce weight and part count, so I built up a 'one-legged' version.
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This guy is much lighter and works just as well!
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