[eric__cartman]

That's a very low tech solution. What we need is an internet connected mug that senses with a camera if it's about to be set on top of a piece of paper and starts beeping uncontrollably.

With a firmware update and an additional charge to the customer a model for detecting polished wooden furniture could also be used.

[sho_hn]

It also needs a permanent internet connection, as the inference for the paper detection is run in the cloud, and a subscription to keep it working.

I call it No-SaaS, No Stains as a Service.