For a while now I have wanted to make plaster casts of wild animal footprints. You can make them from plaster of paris, using the impression of the animal's footprint as a mould, then you have a permanent model which you can take away showing the bottom of the animal's foot.
I did these ones about a month ago, before the weather started to get cold. When it gets colder, it takes longer for the cast to set, so if you are in the UK this might be something to leave until next spring. Here's how I did it (and my way wasn't perfect !)