If there is a need for additional yews, but you do not want to buy, then you can make them from pipes and a corner. It is not a common solution to use turns for pipes.
The basis of the future tool is a steel plate, the entire structure is built around it. The channel will be the moving part of the tool, a plate with a hole from which the threaded rod will exit will be welded to its end.
The final stage can be considered painting, the author of the video chose a matte black color. Perhaps the new yews are not as durable as the cast iron factory, but they will also serve for many types of work.