| thenobledrake |
The spell's text is pretty explicit in regards to how you can shape it.
"You can shape the wall's path, placing each 5 feet of the wall on the border between squares." <--this bit of text is the most restrictive, and thus the most important in determining the valid shape options. It also makes it clear that you can't make the wall thicker - though you can potentially get a similar result if you can shape the wall across an area, then move 5 feet out, then cross the area again so that you've then got the wall covering opposite sides of the same squares.