If you have a CNC mill and don't have a plotter or a vinyl cutter, with these tools, you now have a plotter and a vinyl cutter. Both are constructed on the same theme, a spring loaded cutter or ink refill cartridge. The reason for the cutter or the cartridge being sprung is that it will keep the cutter or pen in contact with the surface when plotting or cutting. The surface sometimes will be uneven, so they will ride up and down keeping them in proper contact. These tools would be programed just like any cutter to go from one position, ie, letter or design. The tool would be lifted to the next coordinates or letter, and then begin again with your design. The only difference would be the depth of cut. You can't exceed the movement of the sprung cutter or pen. I built these tools a few years back without much knowledge of what I would call it, but I just consulted YouTube and they are called drag knives, who knew? The homemade ones that I viewed did not have the spring action, therefore the operator would have to test the depth of cut and program the mill for proper depth, but with mine, the depth is set for the material thickness before cutting. Here is a short video of the two tools, Bob.