The technology combines a top design layer and an underlying conductive copper ink layer that's able to recognize touch, along with a microcontroller that connects to the ink and responds to it. The interfaces work on rough surfaces and curved surfaces, and even in wet outdoor settings. Through the use of the special ink, you're essentially able to connect any kind of stencil design with other gadgets.

[Source: New Atlas. 8 April 2020. David Nield]