but remember theres 2 types of catchcans, some just catch the oil and then u have to empty it,these are basically empty containers which are easy to make, these have to have some sort of breather, the little filters are really good for this as when u just have holes in the top it can sometimes splash out, then theres the catchcans that filter the oil inside it,which kinda have sections in it, inasnt if i was u id drill a hole in the top get a fitting maybe 1/4" and screw it in,then put the filter on top of that,would only cost ya 3 bucks for the fitting and 10bucks for the little filter, there actually little pod filters there cool