I spent last night making this pair of kubotans, also known as a yawara stick. These things are simple but highly effective against close range attackers.
1: Fist compactor
2: A striking surface
3: Pressure points
4: Joint locks
5: If keys are attached, a flail of sharp objects
Those 3 & 4 may take a little know how, but the others don't. Anyone can use one of these things as a devastating tool against an attacker. You can brake bones, take out eyes, ears, nose, you can deliver potentially fatal blows to the head and neck, cause extreme pain that will force an attacker to stop.
I made mine here all fancy because I work with wood for a living, but if you just need something simple, this can be made with any hardwood dowel and a saw. You may need a drill or a reamer to create a hole if you want you keys on it.
Basic easy to find woods that work well:
Basically, anything that isn't a soft pine will work just fine.
Steps to make one:
1- Find a dowel that fits comfortably in your fist. Not too big, not to narrow. You want to be able to make a good fist and also maintain a good grip on it. Slightly larger than perfect is better than slightly smaller than perfect. I ended up using a 3/4" walnut dowel for mine.
2- Take a measurement of your fist from one end to the other, then add 2 inches to that for your total length
3- Cut that length from your dowel and hold it in your hand. Make sure you have about an inch protruding on both sides.
4- Create some sort of grip. You can use sports tape or cotton medical tape, you can use your saw or a file to create grooves. This is important because you need this to stay put when striking with it and also hard to take away from you.
5- If you want to put your keys on it, drill a hole at one end. I'd leave about 1/4" of dowel material minimum from the end for durability. Take a leather or nylon shoelace and tie it so you have a loop that sticks out about 1 1/2" from the end. You should also put a few good drops of superglue on that knot to keep it from coming undone under stress.
Here are some pre-made ones that you can get for very cheap. You can also find these in most self defense shops and occasionally smoke shops. You can find them with spikes or sharp bevels added to the primary striking surface to make them particularly nasty. You can also find them with pepper spray and strobe lights giving you a bit of range as well as the ability to temporally blind your attacker. You can also find small stun gun flashlights that can be used as a kubotan and to stun an attacker.