We recently made a tallow candle out of lamb fat. The red colouring is due to the tomatoes and other ingredients that were cooked together before we skimmed the oil off.
It burned quite well the first time. But since it was a very soft candle, the wick couldn’t stay centred after the first burning.
We are planning to improve the ‘design’ by using a floating wick made out of bottle top (metal ones). In that way, you can also use any other cooking oil that don’t solidify well when cooled, in particular those that have been used for deep frying and are destined to be thrown out.
Update: Improved design
I have made a floating wick out of the empty metal cup of a tea light, by poking a small hole in the centre (enough to thread the wick thru). Then I measured the cotton twine for the height of the jar I was using with extra of about an inch for the top. I threaded the twine thru the hole and made a knot on top. So far, it has worked very well and I could even refill the jar with extra fat. The picture shows the wick that has been relighted a few times. Still going strong!