This can also be used for self defense training if you add some of your sister's lipstick to the edges, that way you know if you have been cut and if it was a puncture or a slash. Although if you have the money, you should probably buy an actual rubber knife.
NOTICE: Yes, you can make a comment that actually has nothing in it. Just because Mepain and I did it two years ago does not mean you can spam up my instructable.
Step 1: Materials
Step 2: The Frame
Picture 1: Build these.
Picture 2: Mutila... I mean "Enhance" a grey connector.
Picture 3: Attach it here.
Picture 4: Attach a red connector here.
Save the other part of the frame for the next step.
Step 3: The Blade
Picture 1: Build.
Picture 2: Attach it here.
Picture 3: Attach the other half or the frame.
Now you will need a rubber band for the next step.