Summary My Ultimaker Orignal Plus uses many M3 nuts that have a 5.5mm hex head. Most socket or wrench sets that I've seen do not include a 5.5mm size (at least not in the US). I have a small adjustable wrench, but it can be clumsy to use in the tight spaces, so I made these wrenches to help when working on my printer. If they don't fit the nuts well, use your slicer settings to adjust the X and Y scaling up or down a few percent as necessary. These tools were designed in SolidWorks. Print Settings Printer Brand: Ultimaker Printer: Ultimaker Original Rafts: No Supports: No Resolution: Doesn't matter Infill: 100%