where to get metal crankcase vent hose?

[George]

On the copper crankcase breather hose adapter, it does reduce from the 1 1/4
inch to 1/2 inch to fit the 1/2 inch elbow that turns behind the block, then
upsizes to the 3/4 inch which fits very nicely into the rubber hose. I
didn't have any 3/4 inch pipe on hand so I adjusted it to work. There is
very little vacuum being pulled through this pipe so the internal diameter
is of little consequence. 
	
George Sidman