To get a tidy speaker grill on your EF01 enclosure or what ever you are using have a rummage in the kitchen utensil draw you may find the perfect template.? I used a plastic sifter lid as the holes were the size I wanted. Draw a center line where you want it positioned, line up the template, drill one hole on the outer circle, insert nut and bolt, drill hole opposite end of template, insert nut and bolt, now drill rest of holes in perfect place.? Hot glue speaker in place on underside of lid.