Existing Holes:
4- 28+mm buttons
Track ball Hole
1 Joystick Hole.
Holes to Add
4-28 mm Buttons
2 24mm Sys Buttons
Spinner Hole 35mm.
Notice the Track Ball take up much more than circle. Plus we need to mount it. Keep buttons away from track ball area. Also Spinner hole maybe 35 mm but to fasten will need much more space so no button over there either.