When searching online I couldn’t find an easy way to edit certain terrain features, so I made my own. Included are .csv and .nmm files for editing the battle platforms, battle backgrounds, minimap icons, and footfall sound effects for each terrain tile.
Both the minimap and sound effect tables come with a definitions event to be included as well. The platforms and backgrounds are simply hexes.
Compared to characters, classes, and items, I think custom terrain is a sorely underdeveloped aspect of romhacking and that may be in part due to the lack of pre-made tools. I hope this will encourage others to experiment with creating their own custom terrain tiles.