Any company with a CNC machine should have the capabilities although mold design is about as difficult as it gets since the two halves must line up perfectly. I would definitely recommend taking in a mold with you so they can see the mechanics of it and you will also need a 3d model of the jig you want to make. You will probably also want some scrap aluminum for them to run a test program on to be sure they know what they are doing since blanks cost like $30 each. Another option would be the Hilts replica mold it is basically a blank mold that uses vulcanising rubber inserts. You basically put the jig you want to copy in and clamp it shut then heat it to set the rubber. It will conform to the jig and then you just cut sprue gates and you are ready to make jigs. Even at $70 they are probably cheaper than getting custom machining done plus you can get extra inserts and make other molds. Also if you are just making a few to do some initial testing you can make pretty good molds out of bondo. I made some 2lb cannonball weights last week using bondo and a racquetball with a screw eye in it as a model.