Yeah, I've seen it. What you're missing is the guy has years of experience, a perfectly calibrated printer, and in spite of that, the device WILL fail eventually. You have to use either polycarbonate (which requires a lot of modification and a heated printer enclosure, but is a little too soft and will distort from repeated impacts), or pla, which is rigid enough to not distort during use, but pretty brittle and has very poor thermal tolerance. You can make up for some of that with carbon fiber infused filament, but that stuff releases into the air during printing, and is highly abrasive to both your hotend and your lungs.