Collect the blood from a freshly killed, healthy animal into a stainless steel pot, and place it over a low heat to coagulate. Stir with a stainless steel spoon to make sure nothing sticks to the bottom of the pot.
Strain out the solids by pouring the contents of the pot through a fine strainer.
Dump the solids onto a tray, and set them aside to dry for a couple of days. Set the tray in sunlight to speed up the drying process, or place it in a warm oven for an hour or two.
Scrape the dried blood into a bag, being careful not to breathe in any dust. With gloved hands, break up the chunks into small pieces.
Clean all your utensils in hot, soapy water.