I am also involved with Antique clocks and clock repair. It’s quite common for an advance clock repairer to have to make a part. I also sell tools such as Sherline Lathes and Mills and used small lathes. http://www.sherline.info
You can knurl a knob by taking an old file and pressing down on the part (round brass knob) while rolling forward in a sliding action. Of course, if you were to do a lot of knobs, Sherline make a rolling attachment for about $50.
I have made some parts to modify camera gear that either was more than I wanted to spend or not available, or I needed immediately. Flash bracket to hold Vivitar slave to sit in front of my crappy digital Kodak so it would block its built in strobe and use my studio White Lightning strobes.
I also recently made an attachment to mount on the Whites Lightning to make the light beam straight, like the one they sell (which I already own) but better. I am next going to make a snoot, also maybe a frensel lens to focus it for a poor mans strobe spot light.
Many hobby machinists are out there and you may be able to fine one that is near you to help you out in making something. Forget CAD, a shop would need to make 1000's. Think analog machining, using the human computer to guide. Making one item at a time is not that hard.
I will post some photos of my homemade photo attachments if anyone is interested. You can also visit my clock website http://www.ClockBug.com and see some of the tools I use and sell. Just remember me you come across an old clock looking for a home. ò¿ó