Use this to override the interlock on a Modela desktop milling machine, allowing you to run the spindle without having the safety shield in place. I've seen this machine in operation at 4 places now and all of them run it without the cover, but usually the interlock is defeated with a piece of tape or something. This is probably a bit more reliable, and when you're planning to cut an 8 hour job overnight, why not go for "probably" more reliable? This is an STL version of the model created by https://grabcad.com/bettak at GrabCAD. They graciously supplied Solidworks files for making the part by bending sheet metal or by maching a chunk of something. I opened the file in Fusion 360 and made an STL from the version of the part that was meant to be machined. I printed the one in the photo using the Makerbot Replicator X2 and it works great. You need to make sure it is pushed down fully when screwing it in or it might not reach the interlock switch. Original at: https://grabcad.com/library/dog-for-mdx-20-15GrabCAD -> Fusion 360 -> Makerbot Replicator X2