Hello, Lemmingangsters.
I've made a level in 3D Lemmings. There are two files attached.
The LEVEL.000 file contains the level information, and the BLK.000 contains texture assignment data for each block. I've explained all this in the technical forum, so I won't get into it now. Just that you will need both files in order to load this level properly.
Anyway, just copy these two files into the LEVELS folder of your 3D Lemmings directory (this will replace the file of the same name, so you may want to back that up first), then load the first level of Fun.