An association exists in Japan just dedicated to guns that shoot rubber bands and here you can find its very cool website. The association has more than 2,500 members!
This is last year’s ranking.
Mr. Asano is the founder and president of the association.
They even publish a world ranking. If you want to be the world champion you have to know that you can use your own gun and you have to be the best at shooting a coin at 5 meters.
In the official website there are many photos of guns made by members of the association and even instructions on how to build them yourself.