Not really a tool this - but just a set of functions in Blitz that allow you to easily use another tool - FSRad - with Blitz. FSRad is a freeware radiosity processor/lightmap generator that allows you to produce convincing lightmaps such as these:
The famous cornell box:

A room I created in Maplet:

Read the readme for instructions on how to use b3d_rad. FSRad must be downloaded separately.
Download b3d_rad here.
The famous cornell box:

A room I created in Maplet:

Read the readme for instructions on how to use b3d_rad. FSRad must be downloaded separately.
Download b3d_rad here.