I needed to use my Dremel tool after not using it for like 4 years. It broke after about a minute. There's a plastic coupler inside between the collet and the motor shaft that had completely disintegrated. I was all ready to order a new part, about $7 on Amazon, when I wondered if anyone had already made one with their 3d printer. I checked Thingverse and sure enough someone had created a print file. I downloaded it, sliced it with Cura, started the print with Pronterface and 12 minutes later I had a new part. The Dremel is working great! I'm impressed.