emPolygonizer2 is a custom operator that allows you to create what is typically called “metaballs”.
The basic technique used by this plug-in is called “polygonising a scalar field” or “marching cubes”. It was invented in the mid-eighties by Lorensen and Cline.
The plug-in consists of a “DLL” file (Windows) or “so” file (Linux) for the operator (compiled C++ code for 32 bit and 64 bit versions of XSI) as well as several VB Script files.
For more information check out the website here.