Donut Cinewhoop Prop Guards

These prop guards are designed to provide additional safety necessary to fly your [Donut Cinewhoop](https://www.banggood.com/custlink/GmvKnlbmDf) indoors while not obstructing the air coming out of propellers. They do not affect the flight performance as much as regular ducts do so the quad feels like a normal un-ducted 3", just a bit heavy. They also save you about 10 grams of weight compared to the default ones, and still provide about 10% efficiency increase.

There are two versions, a shorter one for 1306 motors, seen on the pictures, and a taller one for 1408/1507. The original version of the guards is hollowed on the inside to save weight, but I also added solid versions in case somebody wants to experiment with infill patterns. Those models have "solid" in the file names.

Extra parts needed:

* 4 × steel M2 20mm screws with button or socket cap heads
* 4 × steel M2 nuts

Filament choice is very important here. Regular rubbery TPU does not work, the guards come out too