I've been doing Inspiration Stones for years. They seem to snag the heart of many, including myself. Beautiful, smooth, rounded beach stones - rolled smooth that way from glacial action (Whidbey Island is in essence a glacial dump... :) and the waves and tides of the Salish Sea (or, another name, Puget Sound.) Now we offer my stones in the gallery for a small price.
The secret for writing: Micron Pigma Pens, #1 or #2. I use these pens for so much - my Fantasy Houses, for instance. Archival and permanent ink. I've had one stone outside in the weather for years and it still looks the same (except for a bit of moss.)