Of course you can not only throw knives but virtually everything that comes to hand: screw drivers, large Nails or old scissors (these will yield even two throwers :-) Because these things tend to be lightweight, they can be thrown indoors (see Knife throwing lite by E. Sackett).
As an alternative, take some piece of steel and built a throwing knife out of it (see gallery at Throwzini).
The following instructions have kindly been provided by DreadDave, who got the idea from Throwzini where you can also find photos.
As material, you will need a metal coat hanger (the thicker the wire, the better). Cut it in the middle, then on the outside, leaving 2-3cm after the bend (see picture). Crimp this bend down to meet the shaft and sharpen the other end.
Now you are ready to throw this spike (grip the pointed end for best results) into a target that is not too hard: Get hold of some styrofoam or other similar insulation material, and wrap it with tape to make it more durable.
Like DreadDave said: Great rainy day indoor fun!
Fire throwing knivesMarkkus Freitag collected some hints on burning throwing knives.
detailed instructions on how to throw cards.
The throwing spike has a very appealing design, it looks like a weapon out of a science fiction movie. It has a length of 22cm and is quite heavy with its 230g.
You can throw the spike like a knife, the diameter of 20-28mm permits a hammer grip on both ends: Gripped by the tip, you have a good portion of the tool in your hand; the handles features a groove in which the middle fingers fits naturally if hold here, thus the spike will stick out of your hand quite much. Because the center of gravity is not in the middle, a funny phenomenon occurs: from the first distance, you can throw the spike from the handle or the tip, it will stick either way! It just has to hit the target very straight, a leaning to the left or right will not be forgiven. It is no problem if the handle is up or down a little when the spike hits the target, here the tool is nearly as forgiving as a knife.
The spike is manufactured by the hobbyist M. Hopf from Germany on his lathe. The idea came to his mind when he was lathing a spinning toy for his son. Whereas the first tries were rather fragile, the new models are very tough and the tip can be screwed off and replaced separately. The manufacturer is also throwing the spike with the hammer grip.
Anybody interested in owning one of these beauties please contact Mr. Hopf. Every spike looks different because, as he says, "the design starts with the work".
Every throwing spike is unique.