Is there anyway to add custom maps to the asset editor?
Do you mean adding your own created materials to the Categories? Could you give an example of what exactly you’re trying to achieve?
There is currently no way to store texture maps independently. You would need to have a dummy material created in order to store maps within.
The upcoming V-Ray Next for Rhino’s UI will allow storing individual textures in the Asset Editor, as well as instancing them.
Kind regards,
Peter