Not to detract my previous post, but after my initial gush of enthusiasm I do realise the shortcomings of Lem3Edit for creating custom levels - such as not being able to conjure up new tiles from scratch instead of cloning existing ones, for example. It does make editing Lemmings 3 a bit impractical, but still certainly do-able.
This just increases my respect for Clam Spammer for having fashioned 30 levels of his own. As for being "amazed", well, I was pleasantly surprised by the interface when I loaded it up at first. It's good stuff! I'm "amazed" that I didn't give it a try sooner!
Heh, I'll try to tone down my oh-wow-gosh reactions in future.
It comes from being away from the forums for a while and then coming back to find so many new delicious-looking pies to dip my finger into, if you'll forgive the dodgy metaphor.