Print: x1 MAIN_BODY_M6… and x2 STOPPER_M6…
Hardware: X2 M6x20 bolts DIN912 and X2 M6 nuts DIN934
Settings: 3 perimeters and 30+% strong infill
The author remixed this model.
Enlarged holes to fit M6 nuts and M6x20 bolts
.blend file is included, for convenient modifications