A while ago at a robot competition, my friends were playing with solder wire, making flimsy little swords and hitting each other with them. Later, I was wondering if it was actually possible to make a usable blade with solder, and so the Solder Sword was born. (Ok, its really just a little knife, but it looks like a miniature sword.)
Step 1: Materials & Tools
Scrap pieces of waste solder
Whatever you want to use for the handle and sheath
Anvil (I used a metal weight)
Step 2: Casting a Solder Ingot
I started by making an aluminum foil mold in the shape of a long bar, and melting solder scraps in it using the soldering iron and candle.
Step 3: Forming the Blank
I hammered the bar flat using, well, a hammer. Solder is brittle, but you can make it easier to flatten by holding it over the candle with pliers. If it does break, you can solder it back together using the iron. At the end you should have a long flat bar of solder.
Step 4: Shaping the Blade
Form the rough shape of a blade using metal cutters. Then, you can use a file to create the edge and smooth out the surface. Leave a segment at one end unsharpened for the handle. I recommend sharpening the blade with a stroking motion, as if you were trying to carve the file. Wear a dust mask and goggles, because you don't want solder dust in your eyes, or your lungs, or in your body in general. Even if you used lead-free solder like I did, it still has metals which aren't good for you. Anyways, continue filing, until you sharpen it to your satisfaction (which I doubt will happen, considering how soft solder is.). Mine ended up with a sharpness somewhere between a letter opener and a fruit knife. When the blade is done, you can make a handle and sheath. You can be as creative as you want with the materials you have on hand. I wrapped the handle in thread, soaked it in superglue, then sandwiched it between two scrap pieces of carbon fiber left over from our battle robot. The sheath is simply thin sheet metal from a 9v battery folded in thirds. I like how the sword has a varied look, with an ancient looking battle-worn blade, steampunk brass sheath, and modern, futuristic looking carbon fiber. You really can't use it for anything useful, as solder is soft and doesn't hold an edge. The only uses I can think of are a letter opener, decoration, to impress your friends, as an emergency source of solder, or to fight off ninja leprechauns.