Oh yea, if you want to try making levels first dl the game and then dl the editor at http://advsys.net/ken/klab.htm (Ken's Page).
You must put them into the same file, and after you make the edit you must run Compress.exe.
Unless you want to have one of the original ken's labyrinth, then have another file for you're edits.
Sadly, if you want to have more than 30 levels (10 per episode) or more than THAT "edit" you must have as many files as campaigns (or episodes). :Angry:
Go to Ken Silverman's website (too lazy to post here, use the search function) and download BUILD. He converted all the Ken's Lab maps into that and you can play/edit them, provided you have Shadow Warrior, Blood, or Nukem 3D. (Maybe you don't, but I'm not sure if he ever released a standalone BUILD simulator or not)
I dunno about that. E-mail Ken Silverman. ( kjs (at) lems (dot) brown (dot) edu replace the (at) with @ and the (dots)s with .) And, of course, you could always design your own levels and be the first ever to do so!