Chippers, what would look really cool would be to embed the tines (spikey bits) into the timber, to give that "recently stabbed" look.
Take an unbent fork and hammer the handle end to make the tines mark the wood.
Drill small holes (smaller then the tines) (maybe 1.5 to 2mm drill bit)
If you're lucky, you may be able to hammer the points over on the back. That'll keep them solid.
You'll need to experiment.