Monoprice Select Mini replacement e3d v6-compatible hotend carriage and mount

This is a replacement carriage and e3d v6-compatible hotend mount for the Monoprice Select Mini. It supports a 40mm heatsink fan, 50mm radial part cooling fan, Prusa R3 angled fan duct and blower fan support, and GT2 x-axis belt. Parts are held together with M3 socket head cap screws and M3x4mm (1x for the fan duct) and M3x6mm (4x for the clamping face and 1x for the fan mount) hex standoffs hex inserts.

Updated October 22, 2018: Edited the M3 nut version to hopefully make bridging of the nu