fwiw: A few years ago at Burning Man someone had DIY passport stamps. It had their logo on it, then a space where you could put other stamp pieces or just draw something.
-- J. Eric Townsend design: www.allartburns.org; hacking: www.flatline.net; HF: KG6ZVQ PGP: 0xD0D8C2E8 AC9B 0A23 C61A 1B4A 27C5 F799 A681 3C11 D0D8 C2E8