I don't know of any pre-fab sensors for that type of setup, but you might be able to make something like this:
- Surround the plastic panels with welded U-channel mild steel.
-- If you want to make it easy to replace the plastic, use U-channel on the top and sides and a flat bar on the back with screws that go horizontally below the plastic. Remove the screws to pull out the plastic.
- Piano hinge on the top of the panel surround. Hinge point must be forward of the panel's center of gravity.
- A 3x3 grid of horizontal L-shaped mild steel (red) to attach the piano hinges, vertical bar stock for spacing, and square tube for a solid outer frame.
-- The panels should be mounted so the bottom can swing back a small distance and gravity returns it so the bottom is slightly forward of vertical.
-- Consider mounting the L-shaped pieces so the front is 5-10(?) degrees lower than the back. This gives more travel for the hinges, but makes it a little harder to cut the bar stock.
-- Add sturdy stops for the lower corners of each panel to keep the panel from swinging too far back.
-- Lever arm (or roller arm) microswitches on adjustable mounts positioned so the frame striles the arm (or roller) and the stops keep the frame from crushing the switch.
Side view: XX stops and switches
XX for the panel above
------------|
piano /--------- | ==> back
hinge O |
\--------- |
panel |
- A removable front bezel that keeps the panels from travelling too far forward.
-- Remove it to swing panels forward and replace the plastic.
Scott