Ok, so one of the common oddball things about DnD has always been that you can only wear two rings at a time. Anymore and they start interfering with each other, because magic. Now, I've seen prestige classes before where you gain the use of more than just two rings. Most of them amount to copy and pasting all the stats from the Wizard class and then over ten levels gaining the ability to use six to eight more rings than normal. The usual requirement is something like Use Magic Device or Knowledge (Arcana) or some magic item creation feat, usually the one for rings. To me, this seems rather lame and also like overkill. Couldn't the issue simply be resolved with a feat?
So I am thinking something along the lines of a feat with a requirement of the Forge Ring feat. That feat already has a 7th level caster requirement, and I would think ranks in Use Magic Device would be appropriate as well, so we'll call 7 ranks of Use Magic Device a requirement as well. This naturally limits the use of this feat I am creating to arcane spellcasters. I'm not sure how I would go about making it a universal feat, other than just simply making Use Magic Device ranks the requirement. I think if I were to make it able to be taken by non casters I would make the requirements 10 ranks of Use Magic Device or like 5 ranks and Skill Focus in the skill.
Ok, so the mechanics of this feat that I am thinking of are something like a relatively high Use Magic Device check made increasingly difficult by the number of rings you are currently wearing. The check is to stabilize or synergize the energy of your rings so they don't interfere with one another. I'm figuring a base of 20 + 2 per ring you are wearing. So this means adding a third ring makes the DC 26. Most magic items resize themselves to fit whoever happens to pick them up and I am thinking that if you fail the check, the magic rings turn off for 24 hours as their magic fritzes out and they all discombobulate each other. The penalty is that this would make them stuck on your fingers.
So every day, you put on your rings, make the check, and figure out if you can keep them stable for the day. If the check fails, you're stuck with a bunch of irremovable rings that won't work for you. I'm thinking having Detect Magic on while making the check will add a bonus on the Use Magic Device check. Meh, I dunno.