I scored 20 of these rocker switches on ebay for only US$pi, so now I'm looking for places to use them. Here's a design that conveniently mounts a rocker switch onto a 40mm fan without restricting airflow. You just snap the switch into place and wire it up. There's a spacer in the middle of the switch that allows you to mount it along with my 40mm Adjustable Fan Mount (http://www.thingiverse.com/thing:239985) . I should point out that although it's shown in the photo mounted to an X carriage, that's probably not the best place for it if you want to switch it on and off while printing. I have a switch panel version -- similar to my fully printable switch panel (http://www.thingiverse.com/thing:30348) -- that I'll post soon. You will probably need to clip the switch leads a bit -- I didn't want to make the housing unnecessarily tall. Switches: Last I checked, you can still get 20 switches for US$3.14, shipping included on ebay. Search "20 Pcs Boat Rocker Switch"