Silicone rubber is perfect for making detailed candle molds and it could save you a lot of money, especially if you wanted to make more than one. It would also be handy for making a one of a kind candle mold that you might like but never seen before.
You could use a statue, child’s toy or wooden dowels. The wood be be good for making traditional pillars and tapers as long as it was the correct size. You can find this stuff all over the place now, but HobbyCast directed me to Miapoxy. Village Craft and Candle sells a pound for $18 and other candle making suppliers also probably have it.