This is not a fancy shower, so traditional invitations aren't necessary. Use playful scrapbook-themed invites or simple flat cards in colors of the wedding. If you're feeling creative, make your own invitations using scrapbook materials and these ideas:
Print out the bridal shower details on scrapbook paper trimmed to the size of the invitation and accent with a 3-D sticker at the top.
On blank cards, attach a small picture of the bride surrounded by paper or ribbon. Use a fill-in-the-blank invitation stamp for the wording.
Be sure to let guests know that they will be creating a scrapbook. You can ask them on the invite to bring wedding-themed supplies such as paper, stickers and three-dimensional embellishments.