Guys, a few things.

- I wouldn't recommend making your own catch can unless you use proper materials. Making one out of beer cans creates the likelihood that it'll collapse when cruising in vacuum.

Plastic is also out of the question because the oil/fuel mix will eat thru the plastic. Next thing you know, you're stuck on the side of the road with a massive air leak and have to take it out in order to get home. A few weeks ago, I emptied my catch can into a plastic cup and let it separate on a bench. An hour later, the contents of the cup were all over the floor with the bottom of the cup fused to the bench. If you use other plastics, it'll just delay the rate of decay of your setup. The end result is the same; massive air leak and a car that will run like crap or leave you stranded.

- This is for a MZ3, correct? I would say a check valve is not necessary. Your intakes do not see positive manifold pressure so it isn't needed. Chances are your crankcase already has a pcv valve. That will suffice.

- Get a catch can that is baffled. Cans with a simple in/out setup and no baffling internals are junk. Your intake manifold will still get coated in crap. I ran one temporarily before I got my Saikou Michi and my manifold looked like hell. All the work to clean my valves was lost in 6K KMs of driving. It happened that quick...