Avast Thar Matey,
An interesting question to be sure. I am not an expert on Zendrum history, but I believe that way back when ships were made of wood and men were made of iron, Zendrums were made of plastic. However, the fine folks at Zendrum found that the plastic Zendrum presented several problems. In addition, the plastic Zendrum did not have the visual harmony and look of art that the wood Zendrums are. Making a Zendrum out of wood allows for greater the freedom of expression on the part of the customer as there are many more choices of color, patterning, etc. Plastic does not allow for that much freedom. If Zendrum was a mass produced production line item, plastic might be the way to go. Personally speaking, I prefer the work of art that is the Jolly Roger Zendrum ( a unique, one-of-a-kind instrument).
So now, ships are made of iron (actually steel), man are made of plastic, and Zendrums are thankfully made of wood and worth every penny pf their cost.
Fair Winds and Following Seas,