Do you have a link to the video, were there printed on paper or 3D printed.
As I said I have done it and I used paper, don't have a photo for gears but this is one for a form tool, printed 1:1 and cut out a piece, laid that on some gauge plate and used a sharpie to mark where to remove metal. remaining bit of paper can be used to offer the tool upto as you get close to shape..


And an internal gear where the cutter was shaped using teh same method
