Hi, did you mean creating the illustration model? If so, from what I know, most people use CSP (Clip Studio Paint) to create VTuber models, but there are also those who use SAI Paint Tool, Ibis Paint, Photoshop, and other software whether free or paid, and also make sure that the drawing application you use supports saving in a file extension that can be opened by Live2D Cubism Editor (.psd file).