There are a number of ways this could be achieved; but, there are some basic application issues that must be addressed.
For example:
1. Is this assembly associated with a manual or mechanical operation, ie what is happening between the indexing steps, what should trigger the indexing; and, is the loading to be performed by a machine or human?
2. How precise does the indexing positioning need to be for proper operation?
3. What happens after the holder rotates for unloading and is this performed by a machine or human?
4. After unloading does the holder need to automatically return to the loading position or can this be dom\ne manually?
5. What speed of operation is required?