Tifa's right arm bracelet (materia carrier):

The smaller inside diameter is 50 mm, you can scale it up according of the size of your wrist but you have to scale all the other pieces also.

The arcs were the materias are placed have a square hole beneath where the golden pin would be to insert a micro switch of 5.8 mm if you would like to put leds inside the materias to light them up.

Is up to you to choose 2 from 3 arcs to glue to the main body. No materia, 1 materia or 2 materia.

Wristband:The inside diameter is 55 mm, you can scale it up according of the size of your wrist. Is the same of the left arm, so you can print it twice.