I honestly don't know I have left the subject of japanese weaponry behind.

When in construction of them when I was younger I used a helpful website/ search engine known as google. Now I know we have newer and better things in search engines and call me old fashioned but I like to use google.

i am mortally offended........ nah just kidding those look pretty good. Nice throwing teqniqe( yes i know its spelled wrong) there are many techniques but hey if it works for you.... there is a nice site called [secrets of the shuriken do] that is very helpful with techniques for throwing. but .... you cant beat the original unless it sucks like those coat hanger ones.. shudder.So.... cool keep at the shuriken WOOT!!!!!!!!!!!!!!!!!