Finger Hex Wrench - 4mm and 1/4-inch

Remix of the very cool "Finger Hex Wrench" by RonaldWalters at https://www.thingiverse.com/thing:3985566

I wanted to challenge myself and do a complete from-the-ground up redesign (reimplementation?) of the original finger wrench in OpenSCAD.

Here are some changes and improvements I made:

• Still has 1/4-inch hex version
• Addition of a 4mm hex version for compatibility with iFixit style mini-bits
• Changed the magnet to a larger 10mm diameter by 1.8mm thick rare-earth magnet. This magnet is able to hold the finger wrench to a magnetic surface (even upside-down!) and also holds the bit in the wrench.
• The magnet now mounts on the underside. I recommend using supports for the magnet cavity.
• Removal of all fillets and replaced with chamfers, which makes the underside print cleanly with no support (apart from inside the magnet cavity).
• Full source code included (SCAD and SVG)
• 4mm hex-bore is oversized by 0.46mm to compensate for well known issue with 3d printers undersizing holes
• 10mm magnet hole size is oversized by 0.4mm

See the source code for an equation developed by Joshua Kuhn in his 2015 Master's thesis relating to oversizing the 3d-model holes to get accurate holes in 3D prints:

https://repositories.lib.utexas.edu/bitstream/handle/2152/31972/KUHN-THESIS-2015.pdf?sequence=1&isAllowed=y