Here is a more robust single channel relay box.  I wanted to have Octoprint control the psu of my 3d printer through a relay and found existing single channel relay boxes to be severely lacking.  This one has been designed for 3d printing, is heavier duty/thicker, is able to securely clamp the cables down and has a lid that snaps down with clips that don't instantly break off.  

Supplies Needed:

• 4 x m3 x 10mm thread inserts
• 4 x m3 short bolts for screwing the relay board down
• 4 x m3 bolts for clamping the cables down
• 1 x 5v relay module here: [https://www.amazon.com/dp/B00LW15A4W?psc=1&ref=ppx_yo2ov_dt_b_product_details](https://www.amazon.com/dp/B00LW15A4W?psc=1&ref=ppx_yo2ov_dt_b_product_details)

My printing settings:

• .6mm nozzle
• .36mm layer height 
• 3 perimeters
• 20% infill

The initial tutorial I followed for this was from here: [https://www.instructables.com/PSU-Control-With-Octoprint/](https://www.instructables.com/PSU-Control-With-Octoprint/)

• The box provided in the tutorial is unusable.  It's not designed for 3d printing at all and is not able to safely hold the cables or board in the box.