Concrete Knife Challenge

Someone challenged me to make a knife from concrete. Watch the video to see how it turned out. It's quite surprising!

In turn I want to issue the same challenge to you. Make a concrete knife and send us a picture or short video. Who ever makes the best knife will receive a special prize from us. (it will be a concrete related prize)

I want to see your creations too! Show me what you can do with the help of ConcreteConcrete and Grey Matter!