Render all you fat down - we did our outside slowly over on a camping gas cooker over a period of about 3 days. When piping hot put it into sterilized jars, put the lid on and turn upside down and allow to cool. Make sure you jars are not too hot otherwise the hot fat will crack the jar.
If you store in a cool place, larder, pantry or fridge you will be able to make the most amazing roast potatoes, and I used it for the hot water crust pastry for the pork pies.