host??? cool??? 18650 batteries???
i suspect you are building a pointer...
first... you will never get 2w (at least not for a very long period of time, before you fry everything)
second... you are trying to build something extremely dangerous, i am not very sure that you will find much help if you don't state in more detail what exactly it is you are building
a cool host for a lab style laser under 40$ is any dead dpss module, that you can rip the internals and use the housing. (maybe a bonus tec and fan, or even better, a bonus psu, too)
"its called character briggs..."