Here's a shiny new level set I made earlier today. It's longer than my other set, with 7 levels that aren't endings or beginning rooms.
There are 3 endings.
The main difference is that this one has a greater emphasis on puzzles. It uses the item duplication glitch a lot, but there's still quite a lot of variation in the puzzles.
The download link is http://www.forgottenplanet.com/caillan/pteriworld.rar