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Update Oct 28., 2019:
Some of you have asked for the parts I used:
Bitholder with Magnet, i.e. TOOLCRAFT No. 1614136, or Wolfcraft Bitholder Magnet  60MM 2426000, or Gedore RED R47110014 3300147
Adapter ¼" to ¼" to mount standard nuts, i.e. Proxxon No. 23701
Update Mar 3., 2019:
Published a Bar to help for not so strong hands. Allows additional force but be carefully with higher torque values (>3Nm) some support is needed to prevent from breaking. See pictures and comment section. Printed mine in 2.5h with 25% infill and PLA.
Update Nov26., 2017:
Published my Torque Measuring Lever (http://www.thingiverse.com/thing:2670493) to easily test the parts with a simple scale. :)
Update Nov 23., 2017:
Added 4.0Nm, 5.0Nm and 6.0Nm cases and rotors. More than about 3Nm is not possible without the bit holder is glued into the rotor, otherwise it would slip. 3Nm means about 100 kg on the edge of the plastic hexagon. I used…