Bead thermistor mount for 30 series extrusion

Print with 0.2 or 0.25 layers, typically ABS or ASA for RatRig users.

Use a small zip tie to hold the thermistor in position. The glass bead should be held flush to the surface or slightly below, so it gets good exposure to air, but is protected. There exit channels for the wire in two directions. The overall compact size allows other wires to pass behind the mount (ie, next to the exposed zip tie).