I was blowing glass and I thought hey, cannon balls get a double mold. Why doesn't blowing glass get a second pipe?
I don't know what it would look like, where it would come from, or if it would work... but I thought, hey that would be neat.
Main use case, blowing glass
Most irons blow glass so it would be used... probably.
Speed up a tedious grind(totally not posting this because I have to blow a lot of glass)