Yawara sticks are a traditional Japanese martial arts weapons that were used in times past by police in a similar way to night sticks or kubotons. They are a great weapon for beginning karate students that do not know a weapon kata to use in tournaments, since they can just be held in their fists as they run an open-handed kata that they already know.
For information on how to use these in combat, I would recommend "How to use the Yawara Stick" by F.A. Matsuyama (1948), which can be found in PDF version online. (http://www.scribd.com/doc/3062624/F-A-Matsuyama-How-To-Use-The-Yawara-Stick1948-68-inches-length)
(item numbers are from www.lowes.com)
7/8" wooden dowel (Item# 19385, $3.78)
2x Copper 3/4" pipe caps (Item# 21664, $1.21ea)
Black high-gloss spray paint (Item# 113549, $3.98)
Gorilla Glue (Item#152243, $4.99)
If you already have the paint and glue, then the cost works out to be as little as $3.68/pair if you get enough caps for 3 pair (which is what you can get out of a single dowel rod). Otherwise everything all told is $15.17.
1. paint dowel black
2. Cut dowel into 6.5" segments
3. Gorilla glue the copper caps on the end
If you want, you can get a gold paint pen to write your name on there which is what I did when I presented a pair to one of my students.
When using the spray paint and glue, be sure to work in a well-ventilated area. Also, be sure to read and follow all safety precautions when using the saw.
Be sure to follow the directions of a competent instructor when using the Yawara - though simple, they have the ability to cause great injury if used improperly. I make no claims about the legalities of making Yawara sticks - while legal that I know of in the USA, there are some countries (aka, England) where it is illegal to own these.
Photo from "How to use the Yawara Stick" is in the public domain, having been published in 1948 per http://copyright.cornell.edu/resources/publicdomain.cfm