"A decade ago a very big toymaker got into some serious trouble over this issue.
Had to close a very profitable multi million dollar company for that.

"if my memory does not let me down; it was some sort of Meccano thing.
And they has a very nice promotion constructon picture on the cover of the box.

"Problem was; You had to buy 2 boxes to have enough parts to build the thing.
The lawsuit got out of control and the company had to close."

That example has nothing to do with using someone else's copyrighted material.