I made the follower board by machining the outside and the depression on my CNC. I made the depression deeper than it needed to be and then dripped hot wax into it and seated the pattern on top so that it would sit flat on the follower board. It worked like a charm.
Here is the casting complete with a steel swivel dowel cast into the part. The gib is also installed.
Here it is assembled with the lock-down tabs installed.