As mentioned before if you wear tunnels rather than plugs you can pass ear wires through them.
Ear wires can be any shape you like too, and dont have to be the traditional fish hook or kidney shape you are used to seeing. You can make your own any shape you want.
To Fit in best with what you are trying to achieve I would make your own ear wires in a triangular shape like this as they will hang nicely in your plugs/tunnels whether they are quite long or shorter:
You can them hang what ever you want from your ear wires as normal.
You can use whatever metal you like, if it will be passing through a tunnel not your ear.
Some people wear a normal earring on the outside of the plug/tunnel, If you plan to do this I would reccommend you use sterling silver of niobium wire.
Also if you have metal sensitivities the best material for ear plugs are hardwoods - these don't go funky in your ears as they have a close grain, and are quite easy to find online.