Knife?

How would I go about making a blade for a knife about six inches long? Also, I need ideas for what to make the pommel out of. Thanks.

EDIT: To be more specific, I want it to be an aluminum blade, and made from something I could find at a cheap price, and would require little to no machining, both for the pommel and the blade.

I have no idea what your looking to make, do you want a small "saber" or are you wanting to make a real cutting knife?

Well you probably wouldn't want to make a knife blade out of aluminum, and actually unless you own an anvil and a small furnace the best you could probably make for yourself would be a slightly sharpened piece of sheet metal, which is also not so good. It sounds like you don't have a lot of tools and/or experience in knife making either. I suggest another route altogether.
What you may want to do instead is just look around for a good cheap knife that you can sacrifice. Ebay is a very good place to do this. It will be easier and probably cheaper to buy a finished piece and replace the handle than to make your own blade.
Perhaps you could give us some more details about what you're trying to do here and then we could offer you better advice.

It would just be a "show" knife, that would just look good attached to my boot on my Jedi costume. It would be kind of an assassin knife, long and narrow.

Oh, like a rambo hunting knife. Why don't you just make a "handle" and make the blade from wood, and just keep it strapped to your boot. No one would know any better, and you wouldn't get in trouble for having a "real weapon"

I would look into the martial arts supply shops
there are plenty online. Throwing daggers are likely to get you what you are after, unless you have the home shopping channel, then just wait until about 2 in the morning and they will start cropping up like mad. At one point i almost bought a warlock, came with 5 other swords for $150. My Hottie(fiance at the time) talked me out of it, oh well

Even if it's just a show knife, an aluminum blade cut from metal sheet will look terrible. If it's going to remain sheathed the entire time I would suggest you follow Valeon's advice. Nobody will ever know that the blade is made of wood. If you want the blade to be visible then check Ebay like I suggested or martial arts stores and HSN as Trogdor suggested. A cheapo knife from one of these sources, while it's nothing you would EVER want to actually use, will be perfectly fine as a decorative knife blade. You should be able to get something for just a few dollars if you look long enough.

Good ideas. I would go with the wood blade and use chrome paint if you plan on wearing it to conventions and things of that nature. They owuld never let anyone carry in something metal and pointy like that. (I don't think.)