It's called contributory infringement.

If I supply you with tailored parts necessary to perform/make a patented invention then that's contributory infringement.

In the US Findlaw says:

"Contributory infringement occurs when a party supplies a direct infringer with a part that has no substantial non-infringing use. Literal infringement exists if there is a direct correspondence between the words in the patent claims and the infringing device."

http://smallbusiness.findlaw.com/patent/enforce-patent/paten...