Summary There's very little info online regarding how to wire a filament runout sensor properly on "compound motherboards". Schematics barely exist, are outdated, or simply doesnt have data you seek. So i hope to help by keeping it simple. This applies to motherboards out there like my OSOYOO MKS Base v1.5 board and my Hictop red MPX .3 Made this to work with regular end-stops micro switches. (This may work with regular ramp boards, but i dont have one to look closely and or personally confirm, all my boards are the "compound, all in one" motherboards) Hardware needed: Endstop microswitch with pigtail connector Four 3mm x 1.5mm magnets M3 x 5mm screw M3 Nut Software side of things: This applies to Marlin!! Specifically the latest version as of 7/20/17 (v1.1.4) There's 3 changes that must take place: (1) Enable filament runout sensor on Config.h (2) Enable advanced pause and adjust values to what you want your machine to do (3) Make sure the right pin is used by firmware The changes are explained in the text file attached. If i paste code here, thingiverse would make a mess of it, and look all weird. This works even when using Octoprint. Print Settings Printer: Hypercube Rafts: No Supports: No Resolution: 0.20mm Infill: 12% Notes: Lid is held together with two pairs of 3mm x 1.5mm magnets. This is intentionally designed to float between the extruder motor (bowden setup) and the filament roll as seen on the pic attached. I didn't want to make any brackets because it will be more cumbersome for my setup. For me it causes no extra drag. Im sure someone with direct drive could mount it. I will leave up to you to design your own bracket solution, using a longer screw would suffice to attach this.