I did my son to study time. Time can be stopped like twisting the gear, and moving the minute hand. In this case, the arrows rotate as on a real clock - one revolution per minute is equal to one hour's movement. The dial was printed in a call of color with a stop and replacement of a filament. The dial and hands are fixed to the glue. I printed ABS with plastic, so I used acetone. The dial can be deployed so that the control gear can be on the right or on the left.