Parts

6pin 3mm micro-fit Molex plug - Digikey - $3.50 for 5pcs

24gauge crimp pins - Digikey - $3 for 10pcs

Optical sensors - Ebay - $3 each

4pin wiring harness - Ebay - $3.50 for 5pcs

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Tools

Soldering gun

Heat shrink

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I still have to do the write up for this one.  For now if you are handy with wiring diagrams you can use the parts list and the diagram below to wire things up.  Use the 4pin connectors to connect to  the optical sensors.  Then wire up the other end of the cable like the diagram and push them crimps firmly into the harness.  

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