Another post just reminded me I've never shared my frame on here before. (Used by me, not designed by me)
Everyone always seems to share the same popular frames, but I like unique ones.

Check out the ZMR Slim.  
It's a frame that uses ZMR 250 arms (cheap and abundant) to make a 210mm X-frame.  
They also have a "unibody" version (this is the footprint) that I helped design because I loved the frame so much after flying it for months but I wanted a frame with arms and body as one plate.  

They have other unique frames on their site.

The ZMR Slim is a great idea.

will use the thread for the same:

http://mokaframe.com/moka-simplex --> Z Frame !
and
http://mokaframe.com/frame-1/moka-micro-2 --> not the lightest 3" Frame but with a total different approach how space is used. Vertical mounting of FC

That Simplex is really interesting. I wonder what it would fly like with angled motor mounts.

Man, all their frames are really interesting and unique. Good find!

A friend of mine showed me this recently http://www.exversadesign.com/product-pag...1696b93742
Not sure what FC modifications or channel mixing in the radio or what will be needed to fly it, but it sure looks interesting.

Wow, the Moka Simplex looks great and super tough with 4mm plates on both sides.

Added to my list of potential frames for the next build, thanks for sharing!