DIY 3D Party Invitations or Holiday Cards Tutorial from Manda Townsend here. This is such a good idea – corrugated cardboard and sheet protectors.
DIY Birthday Party Banner in a Box Tutorial from Oh Happy Day here. Lots of punches are listed for this tutorial but you don’t really need them. Sticker paper however is cheap and will make this really easy. You could also sandwich the banner between pages of a card to make this cheaper to mail.