Usually, when you want a servo motor, you simply buy one already made. But if you need something unusual, you can turn any DC motor into a custom servo you can control just like [Dejan] did.

Tolomatic products include the IMA and IMA-S linear servo actuators. These actuators feature integrated Source: Tolomatic, ...

It only escalates from here! Both of these disks go inside the motor. That is, you have to pry the servo’s DC motor apart, take its base with brushes out, then insert the encoder disks.