As a thought experiment, I was wondering how to store something in a box/envelope, and know if someone else has looked at it.
My conclusion was to search for "holographic tamper" on AliExpress, and carefully examine the photos to find models where each sticker has a number and a differently-aligned background pattern. Prices are around $5 for 250.
Then you could use several stickers to seal whatever container, and take photos to record each sticker and its pattern. There are ways to exploit this system, but it probably helps against a non-sophisticated attacker.
My conclusion was to search for "holographic tamper" on AliExpress, and carefully examine the photos to find models where each sticker has a number and a differently-aligned background pattern. Prices are around $5 for 250.
Then you could use several stickers to seal whatever container, and take photos to record each sticker and its pattern. There are ways to exploit this system, but it probably helps against a non-sophisticated attacker.