--- As of February 17th 2017 this design was also introduced in the Liftoff drone racing simulator! See also: http://www.liftoff-game.com/2017/02/17/update-0-8-4-released/ ---

EDIT (May 24 2016): The most recent STL's have finally been uploaded. Months of testing and redesigning have resulted in the currently uploaded files. Most important updates include:

• The body angle has been lowered from 30 degrees to 25 degrees. This improves balance and aerodynamics. The 30 degree angle was too extreme in my opinion.
• Design was optimized for 1306 and 1407 motors. Motor mounts have been scaled down accordingly. (On request, I can still provide some 2204 motors, but I really disliked the 2-3 minutes flight times with those motors. I feel like 1407's are perfect.)
• Extra set of center parts included for a 4 in 1 board ESC instead of 4 separate ESC's. I have no personal preference. Both work equally well, but the 4 in 1 ESC is easier to wire.
• Some subtle 3d features added to the front end and and landing gear.
• Center screws for the 8 mm arms were made more easily accessible from the top.
• FPV Cam housing specifically for the IC120SHS camera (available at Hobbyking).

Recommended parts:

• Motors: 1306, 1407 or 2204 (I prefer smaller motors personally)
• ESC: FVT Little Bee 20A, similar sized ESC's or 4 in 1 ESC board
• Receiver: anything small like the FrSky XSR or X4R
• Vtx: anything works, however the smaller the better. (I use the FXT series Vtx)
• Fpv cam: Turnigy IC120SHS or one of the various small CMOS cams around
• Lipo: 3s or 4s 850-1300mah

I'm considering this design 99% finished. I will not drastically improve of change this design in the future. This one is basically done. However, keep in mind that this design is free for all to download and improve upon. So feel free! (In that sense, this design might never actually be "complete"... ;-) )

Feel free to contact me for further questions and feedback!

EDIT (February 22 2016): I have been hard at work improving this design. After countless hours (I really mean countless. I have lost track.) I managed to eliminate all the minor issues which were present in the prototypes. The orange version in the pictures is the most recent iteration. I'm uploading the new STL files as soon as possible, as well as the SKP files. Enjoy!

This is a 4-inch class drone designed onwards from december 2015 and is still a work in progress. The currently shared parts have some flaws in them, but they are being addressed as we speak.

As I'm convinced that every design - drone-related or not - requires compromises to be made, the philosophy behind this frame is that I almost completely went for esthetic appeal and small size. Even if this required me to sacrifice some weight or user-friendliness. (Even though it turned out quite light and manageable I believe.)

This frame is based around two vertical 1mm carbon fiber plates with 3d-printed parts holding them together. All necessary components (including FPV) fit in between these plates. Additionally, the arms are made from 8mm carbon fiber tubes. These have proven to be extremely rigid, as long as you use woven carbon tubes, not pultruded carbon tubes. Basically the ones with the actual "CF-look" are fine, don't go too exotic. Just make sure they are not the plain black CF tubes.