speaking of custom items, i'd like to bring up some things.
master mong still doesn't have it's own unique equipment, and so does mad ray.
master mong should get a lvl10 5star set, or a lvl20 4slot 5star pet.
i think the latter has some good prospects, an ultra-rare dropped pet (0.01% drop chance).
mad ray though is a bit different, that is to say a "set" that fits a scientist should be a lion set.
that means a lvl230 gun, hat, belt (instead of mask) and accessory.