> Use two tiny needles

I'm wondering if it would be possible to manufacture some sort of clear plastic sandwich-like material that contains two separate chemical "fillings", kept apart by a central barrier which, if punctured, would allow the chemicals to mix together, triggering a colour-changing chemical reaction.

I guess the problem would be wrapping the target object in a way that couldn't just be unwrapped afterwards, but maybe a glue could be used which creates a chemical bond that is tamper-evident.