This rudder is made of cloth ...

[GoldfishLord]

I agree that the cloth and the light wooden frame are both materials, but I think that the cloth stretched the light wooden frame is the rudder itself and the final product and is not a material anymore
How is the cloth stretched the light wooden frame a materal?

 

[emsr2d2]

I agree that the cloth and the light wooden frame are both materials, but I think that the cloth stretched over the light wooden frame is the rudder itself and is the final product, and is not a material anymore.

Note my corrections above.

How is the cloth stretched over the light wooden frame a material?

Who said it was?

 

[GoldfishLord]

"cloth stretched over a light wooden frame" is a material.
The final product is the rudder.

@5jj says that.
I wonder how "cloth stretched over a light wooden frame" is a material, not the final product.