This is a minimal mounting system to move your EZStruder to the top of Rostock Max. Routing all the wires is still up to you.
The spool holder will also fit the small 1lb Taulman spools.
You'll need 6 M4 bolts and nuts to attach it to the top plate.
There are three spots on the top of the printer where the extruder and the spool can be mounted. You'll probably want to mount the spool in the spot that you consider the front of your printer. That'll leave the other two spots for mounting the extruder(s). The filament passes through the center hole when it goes from the spool on top to the extruder underneath and the least "kinky" route means that the spool and the extruder should not be mounted on top of each other. But a spool can be mounted over a different extruder (like in a dual extruder setup).
I printed both with two shells and 25% infill. That was enough for the extruder mount but the spool post probably needs something a little more solid.