Tamper proof seals?

In my line of work we use Scale Indicators that are calibrated by Weights & Measures Canada. Once the audit is completed the unit is sealed with a destructible seal and record of inspection is recorded. If that seal is ever tampered with by someone not authorized to do so there are big fines.

So yeah, it would be easy for us to snap those seals and drop custom programs into the indicators all day every day. There's also stupid-obvious methods to prevent tampering.