I made these dino fossils for Vinnie's birthday party. This boy loooves dinosaurs and has an entire triassic period's worth of dino toys and models.
The fossils are made from salt dough - I don't know if it was just me, but we would make Xmas tree decorations from this every year (everyone I've asked has lookd at me blankly). You only really need three ingredients, but we add an extra couple of things to make it easier to work with...
2 cups flour
1 cup salt
1 tbsp lemon juice (supposedly this makes your end product harder)
1tbsp vegetable oil
1 cup water
Mix the dry ingredients, then slowly add the wet ones until you have a not too sticky dough. You might not need all of the water so go slow
Knead for 10 mins until firm but still moldable and rest for an hour or so
Create fabulous sculptures, use a cookie cutter to make Christmas decorations, roll beads or use toy creatures to make foot prints (we also have some skeleton dinosaurs that made ace fossils but I can't find them anywhere!)
You can allow the dough to dry out naturally - around 30-48 hours depending on the size of your creation or pop in a low oven for 3-4 hours
p.s. this recipe makes a big batch, but if you don't use it all you can keep it in an air-tight container in the fridge for up to a week - allow it to come to room temp and knead again before use