Shuriken was not only designed for Ninja. I can say "Ninja used the shuriken, too."
Therefore, some of Bugeisha and Samurai could use it.
Also, some of Shuriken ryuha are still continuing today.
Generally, in Japanese Bugei, the meaning of shuriken is the shape of stick. Not "Ninja star".
Ninja star is difficult to make, and difficult to control of throwing. Also, Ninja star is not strike weapon. Because, Ninja star have some blades and spinning. Therefore, always throwing power is disperse in proportion to the number of blades. And the shape is not convenient for carrying. But it might be easy to throw for instant Ninja in Sengoku period. Also, Ninja star worked as other function tools.
If Stick shuriken is thrown correctly, it is easy to strike enemy. Even if it is not stabbed correctly, strike shock gives big damage to enemy. In the movie and TV show, Ninja have many shuriken. But actually, shuriken is heavy. By my ryuha, it is said that Ninja usually have 9 pcs of shurikens at the maximum. But I think even 9pcs is too much. I think that ninja had 2-3 pcs of shuriken in general operation.
In spite of the shape of shuriken is depends on ryuha, but Ninja must use any kind of object for throwing. At the realistic situation, if Ninja use the shuriken of specific shape, it is easy to leak the information of identity. I believe Ninja never do such a stupid thing.
Yesterday, I made suriken in my company. My company is the maker of machine. The factory lines were closed yesterday. There are so many steel scrap in my company. I picked up some of steel rods, and cut them appropriate length by giant cutter. Factory machine is very powerful. The cutting machine cut even 10mm steel rod very easily. To tell the truth, it is first time of mass produce of 10mm diameter shuriken. Usually, I use 8mm.
After I cut the rods, I used giant grinding machine for sharpening the top of steel rod. It is the one of the most difficult part. I already know what kind of shape is good for throwing. But difficult to day. Anyway, it is also very sensitive and dangerous labor. I was using such a powerful machine. After I was completely covered with steel powder, all of rods became seem like shuriken more than seem like steel rod. Then, it was done abrasion for finish.
Next, I polished all of shurikens. Because these were scrap! These were almost covered with rust. It was hard labor too. Then, the top of shuriken is heated up for hardening and heated up again for tempering. This timing is extremely difficult.
Then, 17 pieces of shurikens were completed! Totally, I was exhausted. This time, I made up 10pieces of 10mm dia. and 7 pieces of 8mm dia. Length is not same because I must not be used to a specific conditional weapon. That is important factor.
DO NOT ATTEMPT TO MAKE SHURIKEN WITHOUT THE EXPERIENCE OF HANDLING CONSTRUCTION MACHINES, TOOLS AND MATERIAL.
DO NOT TRY TO USE SHURIKEN WITHOUT THE PERMISSION OF YOUR SENSEI OR INSTRUCTOR.
I DO NOT GUARANTEE ALL OF YOUR ACTIVITY AND THE RESULT.
I DO NOT GUARANTEE THE RESPONSE, EVEN IF YOU SEND QUESTION ABOUT THIS TOPIC.