Finding cheap sources of wood and other materials to use as targets is just something that you'll get used to doing, especially if you're a tomahawk thrower. Nothing eats a target like a hawk. If you manage to find some untreated wood, you'll be able to use the remains for a barbeque!

Long and short - get some slices of tree trunk from a timber yard or farmer. Yes, the round discs of wood. You can prop them up against a suitable backdrop and you're away. Get one for each knife so you don't risk hitting them against each other. Nail or screw them onto a plank and then screw the plank to your backdrop. John does this and they are easy to change when you need to.

Flat ground in an open space is the best but if you don't have access be sure you allow for the fact that knives will bounce a fair distance away from the target if the blades don't penetrate.

Special thanks to John for putting together the great material you see below.