It basically consists of a cardboard box, an acrylic/plastic sheet/glass, a webcam, some tape, computer, and good lighting (which sadly I do not have).
Yeah, so I tried building it. It's freaking simple, except for the part where I have to cut some acrylic sheet. I've never done it before, and neither did I ever use a scoring tool.
Believe it or not, that is basically it. The surface that you're gonna touch is the paper.
Plug in the webcam, download the appropriate software that is written in the sidebar of the youtube video.
Here's a short demo:
Still, it's a little glitchy because of the lighting. You need a seriously even lighting here because having shadows of your entire hand on the surface can screw up the software because it works by looking at the shadows of your fingertips that are casted onto the paper. Yea, it'll just pick up any shadow and interpret that as your finger.