Create fixed circuits through defined relay nodes

Hello, I would like to create custom circuit with following setups:
A) own bridge => some random middle relay => own exit node; meaning, the traffic should be routed only through own bridge, some random relay and exit only through my own specific exit node.

B) own bridge => own relay => random exit node.

Are these combinations feasible at all and does someone use it? Setup B seems easier? Can you please guide me through how the config should be on each nodes. Thank you!

Fix the information of the bridge node in the torrc file of the client, and the rest, Stem can help you realize your needs.