Garage chain clip

Small clip for a garage chain that trips the "stop moving" lever.
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2014-11-04 - Modified scad to easily change the distance between the clips, reduced the distance to better fit the chain, and reduced size of bump at the end of each clip so that it better fits between the chain links.
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2014-11-05 - 40cm too small... adjusted distance between clips to 52cm
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2014-11-09 - final tweak 53cm and reduced height to 4.5 mm... works!
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2017-12-17 - small tweaks to prevent occasion