Painting from three cave sites, a red linear motif in Cave of La Pasiega, a hand stencil in Maltravieso Cave, and red-painted speleothems in Ardales Cave, was found to be more than 64,000 years old.

Sometimes there are moments when an engineer has to use whatever materials they have to hand in order to complete ... the badge PCB had no solder paste stencil, and the solution was to laser ...

This is the Panel of Hands, El Castillo Cave, Spain. A hand stencil has been dated to earlier than 37,300 years ago and a red disk to earlier than 40,600 years ago, making them the oldest cave ...

You lay the stencil on one of the boards, hold it down with one hand, and use the other to wipe some solder paste across…. and the stencil shifts, making a mess and smearing paste across the board.