I designed a E-pipe body to fit 2 x 16500's in parralel. The top battery terminal connection is still a problem and I had to McGiuver it with a couple of bits of sheetmetal, but it works sell. if you come up with a battery terminal solution let me know please. I am considering putting a usb charger inside and soldering the terminals. there is some spare space inside.

It is a fairly large pipe but it packs massive horsepower with the twin 18500 and runns all day at 30W where I like to vape. The devisions on my black mat is 10mm per square for reference. I will work on a twin 18350/16350 soon if I can find good enough battery cells. That will make it much smaller. I also have a 24mm tank on there. A shorter 22mm dripper and shorter stem will make it smaller as well.

I used a standard 510 connection and a MOSFET as this is the prototype and I had one lying around but you should be able to fit a DAN30 in there( not sure where the screen would fit though and I didnt have one lying around). Printed with support in PETG with 8 of 3x2mm magnets to hold the lid down.

I just realized I have not added the source file. It has just been uploaded with a change from the original STL. I brought the 510 connection 5 or 6mm closer to the body to make the overall length a bit shorter. I also removed the little shelf inside and square section around the button inside. This was so no support it printed inside to the top. Just in the neck. If you print with PLA you prob wont need any support in the neck either. The PETG doesn't do overhang very well.

Pipe body.stl is the one in the pic Pipe body Shorter stem.stl is the shorter version. Printing now. The Fusion file included is the shorter stem version.

The stem is from: http://www.thingiverse.com/thing:183485/#comments

2/12/16 UPDATE. Been vaping beautifully for a few weeks now. I just cut the model in half so I can print with no external support for a even better finish. Also to help with prebuilding a nice wiring harness then just drop it in and glue it together.