The particle render type of an nParticle object specifies the form of its particles. For example, you can display particles as small spheres, streaking tails, or 2D images of your favorite snapshot. Once you select the particle render type, you can add attributes specific to the render type to tune the appearance.
See nParticle Shading attributes.
To set the Particle Render Type
You must apply a material with shading group to the particle object. Tube (s/w) and Cloud (s/w) render types use specific particle cloud materials. You can use any surface material with Blobby surface render type.