All files for the 3D ballparks need to be stored in the /ballparks/models folder, in a separate folder for each park - for example, the default major league ballpark goes in the /default_major folder.

All necessary files should be stored within the park folder, with textures in a subfolder. The exact files stored will vary according to the model format used - for example, Wavefront Object (.obj) stadiums will include an .obj file defining the model, and a material (.mtl) file that defines the location of the graphics files it uses.

All models will include an .ootp3d file once they've been saved in the OOTP editor; this file contains information on the grid alignment, fenceposts, camera locations, and other OOTP-specific data.