bCNC can do z-probing. Not sure what kind of precision you'll get with a 3018 in terms of moldwork, but you'll be able to get some kind of results. If you have a mold you need to scan in multiple directions and dimensions and not just a 2.5D z-scan, you'll need to figure out how to make your machine into a CMM- write a really long g-code probing file based on rough measurements and run some kind of add-on macro to record all the data. There'll probably be some trial and error and programming involved.
