When you are a part of a society where you need to give something on every occasion, it should be wrapped in some artistic envelope and why not make it with old book covers?
I have made several envelopes with various designs using upcycled old brown book covers which were no more useful to anyone. It takes me only a day to design every new envelope.
The things that you require is artistic skill because when you know how to paint a brown paper, then you can create several designs.
These are lovely, but are you using hardback or paperback covers? You stated they were “brown book covers,” I’m not sure what that means and google couldn’t help…brought up every book that had the color brown in it!! LOL