Stu has been telling me about ranger bands and the more I think about it, the more useful they seem. Ranger bands are pretty much just cross sections of bicycle inner tubes but they have so many uses! Stu says:

"Re: ranger bands, I find them possibly amongst the most useful things ever...From one old mountain bike tube I have made countless hi strength
bands which have used in various thicknesses for so many things, even
at a push a hunting catapult/bowsling when linked in loops together.
They are extremely strong and would be good for the top of an improvised
teepee tripod if making a shelter this way. I have used much
thicker/longer sections to do heaps eg: use as sleeves for my neck knife
sheath to stash stuff like in this video: http://bushcraft.org.nz/video/neck-knife-kit
even used as sleeves for tubes of ointment so I don't have to worry
about them denting and splitting in a pack when out with the kids. In an
emergency they will burn when wet re firelighting (if noxiously!). The
black smoke can be used for a last ditch signal fire I guess but you'd
need a whole tube I suppose (easily packed though). Thankfully I have
never had to do this. I am coming to the end of my last tube...I may
need to approach bike shops and cycling mates to secure a fresh supply!"

I might scavenge a tube from the bike shop down the road and give them a go. A great example of a zero cost, multi use item.