Assuming you all know KillerK and his famous K'nex pistol, I have a mod for his sniper rod. It is a very dangerous dart, and seeing how he shot his sniper rod 200+ feet, this dart can go about that range.
Step 1: Materials
What you need are:
-KillerK's sniper rod
-KillerK's gun (optional)
-Needles or nails
Step 2: Breaking the Needle
Here, you are breaking the needle in about half, so the long needle doesn't bend that easily while being hammered. I found that my needles break if you take pliers and bend them. Be careful though, the needle will go flying if you don't put any cover on it. Just use a sheet of paper to cover the dangerous part of the needle.
Step 3: Hammering the Needle
Basically, in this step you are hammering the needle into the tip of the rod. Try and find the middle, mark it with a hammer or two, then hammer the rest in. I'm not sure how much you have to hammer in, but hammer in as much as you can. It is hard because K'nex is very durable, meaning the needle won't go in easily.
Step 4: Taking the Needle Out
Now that you've hammered in the needle far enough, you can take it out. Don't try and use your fingers, they'll just slip. Instead, use your pliers to ply it out. The needle might be bent, so break another needle in half.
Step 5: Super Glue That Hole!
Use your super glue to fill in that hole. After that, use your pliers to hold the needle tight. Insert the needle blunt side first into the hole and let the super glue do its work.
Step 6: Let It Dry, Pl0x
Just let it dry. To make it more stable because my needle looked like it might come off, just fill the whole top with super glue and let it dry over night. The following day, you will have a hard needle stuck in there and you will be able to shoot it at your dart or bulletin board.