Hey Guys and Gals.. Just a 100% Achievement Guide/Walkthrough for those wanting to blast it out quick! :)
Go to 39:30 in the video to see what level and how it is done if you have any trouble.
I left it til the end of the game (But of course you may have either accidentally got this already or just went ahead and did it anyway).
Go to World 1, Level 6. Get the two pieces of Tetra to make a stiarcase.. MAKE SURE there is a gap between the one bit of stairs and the ledge, then simply drop on through