I'm looking for ways of making a cheap scale (doesn't need to be too precise) and I turned to vacuums to use as a countering force (or atmospheric pressure, to be more precise).

I'm thinking of simply sealing a syringe's barrel (the chamber) and then tying a little basket on the plunger (the tail), so I can weigh down the basket (with things I want to measure) and have the plunger move down to get a measurement.

What do you guys think? Is the principle practical for such purpose?

It's an interesting idea.
I don't think the scale would be linear and you would need to worry about friction.

A spring - even a few rubber bands- would certainly be easier to work with.

Edited November 12, 20205 yr by John Cuthber

As JC said, it won’t be linear, and will have a limited range of usefulness as well. But it should work at some level. You can compare the theoretical displacement with some calibrated masses and see how accurate it is. And test the dependence on the ambient temperature and pressure 

Also the expansion will affect a change in temperature from ambient, so the reading may change as it settles toward the new equilibrium. Any moisture changing state would also have an effect.