Compact extruder with symmetric mount and fan support

First version of Prusa nozzle used an asymmetrical aluminium mount as cooling plate. Newer version uses a symmetrical one, that means compact extruder part needs a change. This is my version. Rest of the parts may be obtained from https://github.com/josefprusa/Prusa3-vanilla/tree/master/distribution

Please note I have upgraded this part to the new x-carriage using 30mm of distance between support holes.

Thicker MK7-like drive gears won't fit in the original extruder. I have changed the channel for the drive gear so now it should be possible to use MK7 drive gear (untested).

New version added, now with holes for a 40mm fan and a duct.

New version just added with bearing capture to avoid it from jumping outside of its place.

Two M3x12 mm and two nuts will be used for fixing the nozzle plate to the block.

Two 625 bearings and one 608 are needed too.

M5x66 mm threaded rod will be the main shaft, where a drive gear is attached.

Two M3x30mm and nuts will fix the idler in place (a 20mm M8 rod is needed for the 608).

The large gear calls for an M5 lock-nut, a regular nut with a drop of superglue worked for me. The small gear needs you to file a flat on the motor shaft (no fixing screw).

For fixing a fan, you need the fan version and to tap the two holes with M3x25, you can use two M3x20mm screws then.