if ya really want to make more grenade launchers, I suppose aegisalt is the right material to make it out of? but you could try to make a one handed aegisalt grenade launcher, and then like a two handed grenade launcher that requires solarium stars, sort of like vanilla style.

Already made aegisalt just not released yet

You should make a vortex grenade launcher, it pulls in enemies in it's explosion radius. Also, possibly a cluster grenade?

cluster grenade? see durasteel nade launcher alt, it explodes into more grenades

Oh i didn't remember they had alts.

i think some kind of shotgun grenade launcher thing would be cool.