Well hot glue gun works, but it depends on what kind and if you painted the inside of the bucket. I Painted my satin black and the hot glue did not hold up. What ive found that works if the visor fits good, is glue one side with Goop and use gray or black calking to fill in. Sounds strange but it has worked on my two helmets. The epoxy never worked for me, dont mean it wont work for you.
Testors dullcote is a great thing! But if you do yoru helmet id use it very lightly. Very lite sprayand see how it looks after it drys. If you put to much on it just looks like there is a very dull clear coat on, dose not look all the real.
I did my Beehive bucket like that with the very lite coat. Ask who have seen it, shes a looker!