I recently got hold of some reasonably cheap Special FX wax.
In the past, I have found with the cheaper options, the outcome is not as realistic; also the wax can be quite difficult to use.
The high-end SFX wax is just too expensive for messing around at home; so I highly recommend, if you fancy a go at it, to try Snazaroo™ wax (between £3-£4 for 18ml).
It is easy to handle, the wax blends in really well into the skin and in my opinion, you can get very effective results easily and quickly.
