The hole is sized for a 6 mm bolt.
Printed standing up in PLA with 25% gyroid infill, 0.2mm layer height, supports, and 4 perimeters.
Depending on how well your first layer is dialed in you might consider adding a brim.
The model is written in solidpython2, which compiles to openscad, which renders to stl.
The author marked this model as their own original creation.