He uses a laser cutter to cut Mylar sheets into stencils. [Juan] appears to be using EagleCAD and Express PCB. Both tools are available for free to hobbyists. The first step in the process is to ...

She then lays it over the PCB and marks all the pads with a marker ... and we’ll never use it to replace a laser-cut stencil for a thousand tiny 0201 discretes. But that’s not the point ...