This github repo has a template project with the necessary files to start creating your own assetbundles containg minis, tiles and props (currently only minis are supported).
Easiest way to create a mini is by providing an .obj, .mtl and a texture file describing how to texture the asset.
Info.txt is a json file that determines how the assetbundle gets loaded into the talespire asset database. This is optional to be in the
The protrait png is an optional component to your asset bundle. It needs to be 128x128px in size as scaling is currently not supported.
Here are the steps on to compiling the assetbundle: