the technical problem of providing a channel , which is more reliable , prevents contamination of guided liquids and which can be produced in an easy and cost saving way , is solved by an apparatus , comprising a plastic part , a channel within said plastic part configured to guide at least one fluid , wherein said channel is configured to be used in a medical device , wherein said channel is a y - channel having three ends and wherein said channel is produced with gas injection technique and / or water injection technique . the technical problem is further solved by a method to produce at least a part of a medical device , comprising the steps of producing a y - channel within a plastic part with gas injection technique and / or water injection technique and opening said y - channel to produce at least one opening .