Sand Writing Tray with Tracing Cards & Sand by Callie's Corner, http://www.amazon.com/dp/B00AAGQ8B4/ref=cm_sw_r_pi_dp_rLN8rb0MA14Z4
Geocaching Idaho's most Favored Geocache -
New cache ready to hide #geocache #geocaching
Low Profile Acorn Small Geocache Container
This would be a neat idea for a micro. Instead of a log in a baggie in the walnut, the logbook is the walnut. You'd probably have to use Rite in the Rain waterproof paper though since with no cover, regular paper would get wet and become unsignable.