This is the one even your parents made as kids...

All you need is a dinner taper or plain white candle placed in a milk carton; melt the wax in a double saucepan.

When the wax is melted, grab some ice from the freezer and put around the candle - then pour your wax arond the candle to cover the ice.
When cool tear the box away, let the ice melt and drain away....