Put in an offer on this. Adjustable setpoint, adjustable deadband (difference between 'off' and 'on' thresholds), plug-and-play. Overkill, yes. But no effing around with syringes, pneumatic cylinders, springs and micro-switches. Not my ad. http://www.ebay.ca/itm/Barksdale-Pressure-Switch-E1H-H-VAC-P...

Check out http://www.leevalley.com/en/hardware/pa ... 1994,52400

If your core thickness matched the extrusion thickness (3/8") you'd have a huge bonding area with the top and bottom skins.

Still, you can put a lot of inserts in for less effort and money.

Rob