Start from cubic forms inside Rocket 3F if you are not enought satisfied by the SubDive tools yet existing of MOi! ;)
(_SBridge, _sSplit, _Sscale, by Max SMirnov) + Extrude...
About SubDivide in nurbs :) https://moi3d.com/forum/index.php?webtag=MOI&msg=9689.1

Here random selection inside Rocket 3F

the 2 methods of direct importation from a Zbrush Mini file OBJ



Funny result with the _subdiv_beta9 of Max Smirnov !

More easy with the free MagicaVoxel : a simple Drag & Drop! :)

"Funny result"

Looks like the faces weren't joined, so it subdivided each face individually...

Pretty cool look.

Pointillism

Yes, it's just the option inside the SUbdivision when volume has not faces welded! (so separated)
Your can permit or not the SUbdivision...(preserve corners enabled or not)
Sorry the Plugin is in French even the UI is in English! :)