http://www.gdhlhdc.com/en/products.html?typeid=202903
I would suspect that these are in inside the bathroom scales I have at home, I might even check sometime and they're available from the same supplier.
Is there any reason why can't use them between two aluminium sheets? You could stick in a limit easily enough and maybe even just give each load sensor a donut of silastic as a sealant.
I couldn't use anything like feet in any of my bee yards, they tend to be pebble, or sand.
Image:
I put the parts on thingiverse.
It takes a micro load cell
You screw the top on the bottom of the hive base then assemble the cell and bottom, snap together,
set base on a stand and screw them (all four) down.
Note: I have not used them yet so I don't know if they will work,but you get the idea.