You can achieve this by two different methods:The first is to actually inter-mix different diameter fiber optic filaments. You would choose a base diameter, that is the diameter that would be used for a majority of your stars. Then you would mix in a different diameter filament.
For example, take a 10 x 10 room with an over all star ratio of 4:1.
You would like 3/4 of the stars .75mm and 1/4 of the stars 1.0mm.
Looking at the star calculation table for a 10 x 10 room and a 3:1 ratio for the .75mm filament (keep in mind that this will be 3/4 of the total 4:1 ratio star coverage = 3:1 ratio) you’ll need 2442 feet of .75mm fiber.
For the 1.0mm fiber at a 1:1 ratio (again the 1:1 represents 1/4 of a 4:1 ratio) you’ll need 814 feet of the 1.0mm fiber.
The Second method of obtaining a mix of different sized stars is to install one diameter filament through out, and ‘flare’ the ends of the filament.
Click here for a photo demo on flaring.