Some small objects to make impressions in the dough (Shaped cookie cutters work well.)
Empty can or a butter knife
Toothpicks, optional
String to hang your fossil, optional
How to make it:
Stir the together the coffee grounds, cold coffee, flour, and salt until well mixed.
Knead the dough together and then flatten it out onto the waxed paper.
Use the can to cut out circles of the dough or use the dull knife to cut slabs large enough to fit your "fossil" objects.
Press your objects firmly into the dough. When you take the object out, you have your "fossil". If you want to hang the fossil, poke holes into the edge to hold the string.
Let the fossil dry overnight (and up to two days) and then hang it if you wish.
Tips:
To reduce the drying time, bake the fosils for a short period of time to get the "dough" to harden.