Basic Casting Techniques
To do this, you will need to bring dry plaster of Paris, water, a mixing container, a mixing stick (a paint stirrer will do nicely), and something to make rings out of. Plaster of Paris can be bought either dry, or ready-mixed. It is probably better to get the dry type so that you can mix it on site. It will need to be soupy to make a detailed cast. When you find a suitable track, place a ring around it. The ring can be made from almost anything - a large tin can with the bottom cut out, a paper cup with the bottom removed, a strip of poster board 4 cm
wide and taped together at the ends to form a circle, etc. You can also cut one from a water bottle (for small tracks), a two-liter soda bottle, or a milk jug (the ring does not have to be round). Make sure the ring is larger than the track, and note that some tracks are 15 cm long or more. What a pity it would be to find a huge bear or moose track and not have a large enough ring to cast it! You can also make the cast without a ring, but it is much better if you use one. Once the ring is in place, mix just enough plaster and water to fill the ring up to 2.5 cm deep. It sets quickly, so you will not want to mix up too much at a time. Mix water with the dry plaster and stir it until it is smooth. It should be about the same consistency as pancake batter or apple sauce. Pour it into the ring. Once this is done, you can set out in search of more tracks, or you can wait until the plaster sets. If you set out for more, be sure to come back to collect your cast.
One good way to complete this requirement is by heading to a river right after flooding has receded. There will likely be plenty of easily identifiable kinds of tracks, and the smooth mud makes for excellent casting.
Here is a more detailed guide with illustrations.
