Sethhunter

Thanks guys!
The vacuum forming idea for the spinner came from one of you (enormously helpful) gentlemen, along with the suggestion to build it with a front plate rather than a backplate, to avoid the "ring of screws" commonly used on Albatros style spinners. (I've been assured the screws are a royal headache to remove each time the engine spins a prop loose!) With a front plate, the spinner cone (however it's made) can be adhered to the plate permanently, and the cone extends back past the prop like a skirt. I suppose in this size range, the prop hub offers enough area to properly (no pun) support the spinner this way. The Pfalz offers the advantage that the spinner has [what looks like] a removable center plug, perfect for inserting a socket driver.

Vacuum forming sounds like an important skill in this hobby that I've always managed to avoid, so I'm up for it (and a lathe would just about finish my woodshop!). Especially since some informal quotes I've gotten suggest a custom one-off machined spinner this size will cost considerably more than the engine. Even a block of Aluminum this big is pretty pricey.

Alan - thanks for the suggestion. What is the balloon method??