Ninja swords. Husband made them. They look awesome and were cheap!
Ninja headbands for my son's ninja birthday party. I made a stencil with the Japanese characters for strength and friendship, and stenciled them with craft[paint onto headbands I'd made out of inexpensive white muslin.
Karate Birthday Party Water Bottle Labels by missbellaexpressions,
Karate party treat boxes - karate belts made from flavored Twizzlers