Picking an Open Source Hardware License

I've been wandering around the Definition of Free Cultural Works open source hardware Statement of Principles and doing a little thinking.

I like the ideas behind open source hardware as stated in the Statement of Principles. I want the TuxedoBoard to have a licence that complies with these principles. The difficult part is finding a license that has already been written that can accomplish those principles. I'm not a lawyer so writing one myself seems like a bad idea to me.

The whole open source hardware movement is at the heel of the hockey stick curve. Having a high quality open source hardware license, like the GNU GPL is for software, is something that's definitely needed.

Creative Commons is nice but it is too general and doesn't require enough. The GPL seems awkward when applied to physical things or designs for physical things. The BSD and MIT licenses allow inclusion without releasing source and also seem to apply best to software.

TAPR doesn't quite go far enough and I don't think it completely complies with the OSHW Statement of Principles. For example, under TAPR, schematics or layouts can be distributed in PDF form. That's not helpful! I want a license that requires distribution of things like schematics and layouts in the original computer file format.

So far, I've not found a high quality open source hardware license that I like. I'm confident that one will come about soon but I'm not sure who's going to write it. I'm not that concerned yet, TuxedoBoard is still just an idea, but the time to be concerned is quickly approaching.

Maybe the best bet is a modified TAPR license. But then again, what license is the TAPR license text under? It's copyrighted but does not appear to be licensed for modification or reuse.