Quote Originally Posted by vorpal blade View Post
A chaser can also be a ram with only one testicle.

And I haven't found anything relating chasers specifically to keys, so from what I can find they might decorate but not make the keys. I still think you're on the right track.
I can pretty much guest what the chasers relate to Keyblades;
a) They made the Keyblade itself
b) They're giving the magic power the Keyblade need it
c) They made the Key Chains
d) Mix or all the above