I used a Jeg's universal oil separator on my car (didn't have $100 to drop on one of the ready made ones) and plumbed it with 3/8" fuel hose.
It works great, but the problem I'm having is that after the car sits for a little while the hoses have a little droplets of oil form along the length of them on all sides of the hose. If you wipe it off with a paper towel it just comes back after the next time you run the car and it sits and cools off. I've never noticed it while the car was running, only after cooling down.
I figured fuel hose would work great for this but apparently not. Do I need a different type of hose? Do the aftermarket separators/catch cans all use that hard plastic hose?