How to cast a model foot from an alginate mould. Note: this is not a proper last as a last is not an exact copy of a foot. But I do think this could be helpful for projects like making greaves. The biggest fault I see here is that he casts without bearing a normal load on the foot which, of course, drastically changes the shape of the foot.
Construction of a Foot Mold using a casting sock (specially designed to make shoe lasts), but I wonder if the same can be done using a regular cotton sock and some Plaster of Paris, kinda what doctors do to set a broken bone. After removing the cast, fill with Plaster of Paris to make a perfect copy of your feet.