It is now possible to rotate any block anyhow, making this page obsolete.
The Angle Glitch is an advanced building technique that allows the builder to place blocks at any degree offset from normal building. This is achieved using the rotating tool at the top of the UI to rotate your machine to the angle you desire (there's a small number on the button that lets you know what angle you're at), and then placing a block. This video demonstrates how to perform the glitch.
Already fixed in V0.20