ngry

Being accuracy addict in all meanings I've designed and implemented device to calibrate cave surveying tool distox2.

Calibration Cube: https://bitbucket.org/ngry/distox2_cube/src/
Details about distoX : http://paperless.bheeb.ch/

Also it is quite fun to model ready-to-manufacturing solids by openSCAD and Wolfram Mathematica.