I make them. Once upon a time, I was a professional 3D artist working in the video games industry, until I opted to spend my days at home with my kids, rather than crunching outrageous hours at a studio for several months, about once a year. I somehow fell into this whole cookie cutter making thing by a very strange fluke, but it’s working out nicely so far. I get to use my 3D modeling skills in a very different direction than before.
I model the cutters in Maya (which seems like overkill, I’m sure, but it’s certainly sufficient for the job). I usually start by making vector versions of the 2D art in Adobe Illustrator or Photoshop, then I export the vectors as an .ai (illustrator) file, and import that as paths into Maya. I extrude the mesh from that and once the model is actually completed, I export the stereolithography file and open that in a proprietary program for my 3D printer. It creates the file that the printer uses to actually print the file.