I transfer my hard waxes to empty deodorant container.
I wash them in very hot water to preclean them, reassemble the top end, melt the wax in a double boiler. At the very lowest temp so it will pour. Then fill up the deodorant container about 3/4 of the way. Then, as soon as it starts to harden it put in the screw drive push up mechanism and let it finish hardening. I have at least three empties ready to fill since I have no idea how repeated heating and cooling cycles may affect the wax.
The wax has always ended up perfectly. I have done it with everything from the cheapest Walmart waxes, all the way up to the big can of Fuzion.
This method leaves you with no residue in the big can and a very convenient method of applying the wax to a pad. And the very tiny amount that remains in the push up pad inside the dispenser can always be melted down with the next filling session.