Display of "Minuta" consists of four separate identical number indicators. As you can see in figure 1, each indicator includes two cylinders that are able to rotate relative to each other.
The cylinders have a special printed pattern (left-hand and right-hand patterns are different) shown below. When the cylinders rotate their patterns shift relative to each other and a certain number is formed under a certain rotation angle. The number occupies a quater of the cylinder's outer surface, remaining part of its surface is covered with pattern that carries no information.
Each number indicator should have a rotary encoder. It is necessary for time set up process, when the number indicator's cylinders are rotated by user. Also, the cylinders can be rotated unintentionally.
Presence of the encoders will presumably give an ability to use cheap DC motors instead of less affordable steppers to drive the cylinders.