Here is a how to on building an oil separator (catch can) for $15.
Most units run anywhere from $30+ and just shoving a breather filter on will still allow oil to drip past.
You need a few things from home Depot
You will find these with the air compressor accessories. It is a water separator, and a couple fittins and some thread lock.
Here is a close up of the water separator.
You can discard the filter that comes in it.
Wrap the thread lock around the fitting. (Of course this is easier with two hands.)
It should look like this.
Once you are done, screw the fittings in to the separator. Your finished product will look like this.
It is now ready to be installed in the car.
