If you want to make, (or have made for you), the pieces that you're designing, and don't have any experience in actually making jewelry, then you'll need to do that for a while in order to understand the relationship between the computer model and the actual piece. I use an independent model maker/caster to make my rough castings and even though they do a great job, the castings are never the same size as the computer model, due to shrinkage of molds and then the wax in the molds. Their surface finishes are also rather rough which is due to the way that the wax model is "grown". If you don't take these things into account you could end up with a piece that was unwearable once it was finished, (due to everything being too thin).