I copy the patterns I want and put them in my binder. Then, I'll send the book/magazine on to someone else.
I've done it for recipes too. I used to cut the recipes out, then paste them in my book. Took too much time and sometimes, I would cut into one on the back of the page that I wanted.
I think if you were making the pattern as your own, then yes, you are infriging on the copywrite, but all you are doing is saving. What's the difference in saving just a small part and not the entire book/magazine? Space saver!! But, what you are doing in my opinion is nothing wrong.