You use to could get the splines from atlas too, as far as I know you still can, or you could buy the silver in sheets and shear your own strips. Can do the same thing with aluminum also.
On the rings though, the usual way is to punch the rings out as mentioned already, but I have cut rings from sheet before using A nic/silver ring for a template in My pantomill, and on a 1 to 1 machine, by using the same endmill dia. as the stylus I used, the rings came out the same size. I haven't tried it on silver yet though, but possible it might work, Even if the ID needed deburred that shouldn't be a big deal, as I usually do that as a precaution eitherway. It would take more time to make them that way, but not so much that it bothers me if i need a ring cut that bad, and don't have any. I get My silver from atlas though and save the time, because I haven't used it all that much. If I used them more often though, then I may look more into making My own. Would have to figure out cost/time/waste to decide whether it would be worthwhile though. I'm guessing for me it would be cheaper and less cost effective to continue to get them premade.
I did alittle research a while back on other sources for silver rings, I don't remember the names of the places that I checked out offhand, but most of what I saw wasn't priced much better then atlas, and in most cases they would cost more, but even If some were less, It wasn't enough of a difference to be worth my while to outsource them right now.
Since I don't know of a cheaper or better way, I'm just sticking with atlas for now. The billet strips may be worth buying sheets though because they would have less waste involved in making them. I guess I'm just still waiting to find the best options.
Greg