When I render deer fat I use a large roaster pan in the oven set at 250F with equal volumes of ground deer fat (smaller the pieces the more efficient the rendering) and water. I just let it go for 12 hours, adding water so that it never goes dry. Strain and let it cool outside in the cold of winter to separate tallow from water. I let the dog slurp up the deer flavored water, she loves it.
The remaining water rendered fat then goes into the dry roasting pan and back in the over at 220F to draw the last tallow out.
The first run is super clean and I use that for making soap because it has virtually no odor. The second run is a little darker and stronger in odor and flavor so it goes for grease/candles/bullet lube/leather dressing/etc.
