[prototype] Dobby Drone 3-blade center hub

We use our ZeroTech Dobby drones for youtube and video work. We love the portability and simplicity of the craft, but sometimes we wish it had more stability.

Our solution: a 3-leaf center hub! 

The Dobby's propellers don't weigh much at all and the gain is signifigant, but the tri-blade design cannot fold up completely, hence why ZeroTech made the Dobby a 2 leaf propeller.

Please read these warnings before buying:

• Please clean out the screw holes with a drill bit before trying to insert the screws. Shapeways cannot print the screw column walls thin enough, so they are a tighter fit that we would have wanted.
• Please buy a spare propeller leaf for each rotor. The Dobby typically only comes with 2 leafs per rotor, and this (by definition) adds the ability to have one more. This does not come with a propeller.
• Does not fold up completely, unfortunately. We're working on a v2 that might fold better.
• This is a prototype. It works on our craft, but results aren't certain yet.