In Australia you are required to plug the end of your handlebars before you are allowed to race. There are several do it your self methods available but I’m not sure if the meet the requirements of race governing and licensing bodies. So to ensure your bike passes scrutineering on race day, get hold of a set of colored trick bar ends to suit your ride.
Fitting them is easy but you should take your time and make a neat job
How to fit bar ends on a motocross bike