Build - level editor for Duke Nukem 3D
The Build editor for Duke Nukem 3D is controlled by keyboard shortcuts only. Luckily, there are help files that are attached in this archive, containing how-tos. It has a steep learning curve.
There is also a Windows port of the editor, called JFBuild, in this archive. Just extract it to your game directory and run Build.exe.
I have used this editor to build my maps for Duke Nukem 3D: