Seems like a lot of work for a few drops of fuel. Just about everything I fly gets a measured amount of fuel, like 2.5oz in a 3oz tank or 3.5 in a 4oz tank, so there isn't any overflow out the vent. I waste more fuel out the venturi then I do from the overflow. A month's worth of flying wouldn't amount to an ounce of fuel in a catch can, and it'd be 'dirty' fuel that'd been exposed to contaminants from my syringe, air, humidity, the tank, and the catch can... I wouldn't want to use it anyway. Maybe I'm missing the purpose?