This utility will let you assign floor & ceiling heights without having to first set them up in a level editor!
Its actually a template level which you start out with and you create your own level in it.
The height range is from nearly -32 WU floor to 32 WU ceiling. Its like having height presets for 64 flights of stairs in a starship or building, or a resolution of 512 map elevation contours for your giant outdoor hills, valleys and pools of liquid. Hey, maybe both. There are as many ceiling settings as there are floor settings, so there's room for that underground cave system of yours too!
The included Read Me explains how to first use the presets and later how to delete the preset polygons, if need be.
See the description.