I had parts cast. Took the lower end of a tapered pen, made a core piece to slide into the pen and they made a rubber mold to make wax models that I can later carve with a design and cast it or make another rubber mold to cast many. I had rubber molds made from the tips, center bands and caps also. There will be some tweaking and changes made but before long I'll have a nice selection of parts to work with. The pen you see the silver parts cost around $40 to have cast not counting having the mold made which you can have many wax models made from that mold. My desk sets could be very reasonable priced starting around $100 and up to $200 or $300
I'm thinking that in the spring there might be a chance that I will sell some of these parts. They will take a little work to finish up. If this happens I'll will let the group know. I'm looking for a few people to take a wax model and carve there design into and make a mold from it.