http://trle.net/sc/levelfeatures.php?lid=2921
This level could also be used as inspiration but it is TR2 but I think some will get the idea.
This is actually a great idea, I'm glad the Level editing community is celebrating the 20th Anniversary, looking forward to seeing how people make their levels, I'm in a massive custom level mood, I might start a custom level marathon one day starting from "The Wall" and leading to the present