Credit: Courtesy of Fine Stationery; Courtesy of Paperless Post; Courtesy of Minted; Courtesy of Tiny Prints
(clockwise) Melting Rocket Ship electronic invitation, Mr. Boddington's Nephew, $5 for 30; paperlesspost.com. Bursts of Fireworks invitation, Jill Smith Design for Tiny Prints, $29 for 20, tinyprints.com. Rustica Party invitation, Ringo Baby, $55 for 25; minted.com. Patriotic Stripe invitation, Noteworthy Collection, $52 for 20; finestationery.com.