I think that, of all the CPSC regs, small parts is the one most people are familiar with and the one most easily understood. As such, I'm just going to link to the CSPC's website: here. I do think that it bears mentioning that most jewelry for young children is considered play and, as such, falls into the toy category. Lead regulations are also applicable to toys, as they apply to any and all children's products created for those 12 years and under.
I've seen small parts cylinders for sale on Amazon. There are specific dimensions required so, if you purchase one, make sure they meet these requirements.