A "no drill" Bondtech BMG extruder mount for Ultimaker Original.
Replace one of the back/top frame screws with an 18mm countersunk M3 to mount this mount.
The BMG extruder is then secured using four M3 nuts and four countersunk M3 screws.
The photos shows an older version mounted on an Ultimaker Original.
6 walls makes this model solid without infill