Well, I've also been learning how to
throw knives
in my spare time. I really stink at it, but I'm learning.
Here's some of my
light throwing knives, which are
about all I care to risk, considering that I throw indoors.
Most of them are just cheap stainless steel jobs,
but they work. I actually have eight more just like the two on the left. No, I'm not
rich, they're just that cheap.Of course, if you really want to get into this hobby on the cheap, I would suggest buying spikes. Okay, they're big nails. I don't know when a nail graduates from "nail" to "spike," but that's beside the point. You can find them at any well equipped hardware store, for about 25 cents apiece. The technique needed to throw a spike seem to be about the same as that needed for throwing knives, save for some minor grip changes. The spikes shown on the right are about eight inches long, 3/8" across. About the only complaint I have about throwing spikes is that you have to be careful not to snag the head on the release for full turn throws. (Throws where the knife or spike is released point forward.) I could grind off the heads, I suppose, but it's nice to have something I can replace for a quarter if I lose it, and the extra work drives up the virtual cost. You will need to find different targets for spikes, as you have to throw really hard to stick a nail in a piece of wood. Cardboard boxes work reasonably well in the short term, but a reasonably soft target like the one below seems to work equally well for knives or spikes.
Of course, if you really get on a roll, you can throw just about anything that's roughly the right dimensions. On a good day, I have managed to successfully throw pencils, lengths of music wire, forks, wooden stakes (handy if you get attacked by vampires), screwdrivers... I'm not saying I could stop a charging rhino with a fork, but it is possible to get them to stick if you have a reasonably forgiving target.
Here's my bathroom door, ultimately to become the site of my target. As you
can see from the various holes, my earlier attempts at building a target backstop didn't
work out so well. I expect my damage deposit will suffer. You should see my closet door,
the victim of my first attempts at throwing kitchen knives. You can just barely make out
the two wire hooks screwed into the wooden frame of this hollow core door. I went ahead
and screwed hooks into the door structure instead of the trim pieces above the door, as
I was afraid the weight of the target would pull the trim loose.This spot was chosen because it has the longest continuous run in the apartment, from the back wall of my office, down the corridor to the doorway. This is far enough to allow me to practice half and full turn throws, and still leaves enough room to stand comfortably far away from the wall. This location also has the advantage of being on a central wall, which lessens the chances of my neighbors killing me
This is the first layer of the backstop, designed to protect the door from more holes.
The backstop is made of 1/4" hardboard. It's cut into four pieces and
hinged in such a way that it can be folded into quarters, and stored in the closet.
The backstop is suspended by a loop of cotton rope threaded through holes
in the top, and hung from the hooks mentioned above. I had originally intended to cut a
hole for the doorknob, but this seems to cover it just fine, and the space formed behind
the backboard provides that much more give and protection. Hardboard seems to
work fine, although I would hesitate to throw a heavy knife at it.
Over the backboard, there's a layer of 1" thick foam rubber. The foam rubber is
suspended from three key rings, which are hung from picture hangers driven into the wall
and door.
I threaded a length of coat hanger wire through the top edge of the foam, to keep the
rings from pulling out. The main purpose of the foam layer is to reduce some of the noise
from missed throws. Foam like this can be found at any decent arts and crafts store. It
can be rolled into a bundle small enough to jam into a closet as well.
Here's the back of the target. It's made of two pieces of 
And here's the finished product. The actual target is a 24"x22"
foam archery target, available at any decent sporting goods store for about twenty bucks.
This particular one has a removable center core, which can be replaced for a few bucks,
when the the bullseye gets worn out. The entire target can also be flipped over
to get a bit more life out of it. The target has taken several hundred throws, and
it seems to be holding up just fine, save for some extraneous foam debris on
the floor. If anything, the target is too forgiving. I occasionally manage to
stick a knife in handle first on particularly bad throws. Next replacement, I will try
to get the nine pound density crossbow target, instead of the four pound target I now use.
You can also see five spikes in the bullseye. They were thrown from about
fourteen feet. I won't tell you how many I had to throw to get those, though.