Fully customisable and printable folding propeller set. Including a hub and a spinner.
This is based on the 'Parametric Folding Propeller Generator' by @BouncyMonkey (https://www.thingiverse.com/thing:3506762)
Also the Polyline code that is found in the spinner is from https://openhome.cc/eGossip/OpenSCAD/index.html.

Notes:

1. To use the code: place all the SCAD files in the same directory.
2. You would normally need to edit only the parameter in Folding_Prop.scad
3. Always orient the blades such that the holes are perpendicular to the print bed. This gives maximum strength to the printed part.
4. When printing the hub the same rule as point 3 has to be applied. (though the seemingly obvious choice would be to print it flat without supports)
5. Print at 5-8degC higher hotend temperature than normal. Get that small boost in inter-layer adhesion.
6. The 7x4inch tractor propeller is shown as an example.
7. I would suggest un-comment only the feature you want to(makeHub(); /makeSpinner(); / makeHub();) export as STL and run the render. (cycle through each of them to generate the individual parts and export)

note: This is only my second design on OpenScad. I am happy to take feedback and improve this deign.
Also, if you want to me to add STL files for specific prop sizes, do ask for it. and I will try my best to respond.

UPDATE 05/01/2020: Updated files with the V3 hub. this includes printable supports and a square spinner mount. this greatly improves print success rate.
Testing video at https://youtu.be/r_2c_qXZrNU

UPDATE 05/02/2020: spinner mount dimensions variable. Useful for making super light setups. Minor bug fixes.

DISCLAIMER: Propellers on RC crafts can be dangerous. If you are printing and using this propeller, please use your own judgement and tests for safety.