The print is finished and it works. We're going to do a pictorial here with this one.

Step One. Take the screws out of the top panel of the Rostock.

Step Two. Take the top off.

Step Three. Take off the top side panel above the extruder. Remove the two screws in this panel.

Step four. Bolt the filament holder print to the panel with the screw, two washers, and nut.

Step five. Reassemble everything. You're done.