I needed a tool like Bruce Newman used in his video to align and
shape the valve leather while rebuilding an Aeolian block valve:

https://www.youtube.com/watch?v=2iJOAC4sis8
 
Player Piano Restoration - 1977 Aeolian with Plastic Unit Valves

Using FreeCAD and my 3D printer, this is what I came up with.
Hopefully these .stl files can help someone else.

Kevin Millecam

[ https://www.printables.com/model/1757150-aeolian-block-valve-vacuum-pouch-tool