I have an old Nikon D1h SLR which I loved, but it used horrible Ni-MH battery packs that didn't last long--both in terms of shots per charge, and total lifetime. They're all dead and I can't bring myself to order another one, now that I'm used to li-ion packs in modern cameras. There's one German company that makes a compatible li-ion pack but they don't sell to the U.S. for some reason.

There's a bunch of blog posts about how to take one of these old battery packs and jerry-rig it to accept a couple of rechargeable li-ion cells. But it looks like a pain--cutting open the old pack with a razor blade, gluing in battery tabs, etc. Maybe 3D printing would offer a better way to do the same thing...