A Utility Patent protects the functional embodiment of the invention, not the "design or concept." Some parts of a patent might be covered by copyright in some rare instances (such as a photo).
In other words, a utility patent prevents you from legally creating a functional copy or version of a patent-protected device. (Utility patents do also extend to things such as processes, methods, code, plants.)
But it does NOT prevent you from using that device in a design for some other device. And you can produce your device that incorporates that patented part so long as the part that is under patent protection is one that you purchased from an authorized supplier and not manufactured by you (unless you of course obtained a license to do so).
I.e. you need a license to PRODUCE physical versions of the device protected by the utility patent.
- (That said, the company that holds the patent is under no obligation to supply the device to you. That is, let's say company Squatting Inc. holds the patent on left-handled brass wigimajiggers but they are not actually producing them, or they are producing them but only using them in their own products and you can not buy one — if you require one for your design, you are out of luck until their patent expires and you can make your own left-handled brass wigimajigger.)
DESIGN patents are very different, they cover a design that is "ornamental" in nature, and does not sound relevant to your issue.
Copyright covers an expressive work which may be a design - but copyright wouldn't cover the physical U-joint for instance. Copyright could cover the actual 2D plans for something, but typically not the item the plans create.
On the "plans" issue there are some subtleties, for instance in 1990, Congress passed the Architectural Works Copyright Protection Act which provides some limited protections for building plans.