This is a spool holder bracket is designed to allow for a 50mm shift if you are using the A10M in-line assembly of the spool mount combined with the vertical assembly of the extruders. In the standard setup the filament intake is not aligned with the middle of the spools. 50mm offset is now perfectly aligning the spools and the extruders.
You will need the following parts to assemble the bracket:
5pcs. M3x20 screws
4pcs. M3 nuts
An perfect addition to this setup is the Ender 3 - Filament holder DELUXE (http://www.thingiverse.com/thing:3114139)
As always my designs come with the freeCAD model for your own tuning.
M3 nut assembly
..push the nuts into the bracket.