Different sources show different thickness for the wall. I've seen everywhere from 1.0mm to 1.8mm. I need to know with a high degree of confidence since I'm making an aluminium lego piece of a school assignment, so my wall thickness will be smaller. Because I only get to have one attempt, I can't try it with one piece and adjust the model for a second run.
The image below shows the dimension in question, with this drawing taken from another SE question, made by SE user Bartneck Original source: https://bricks.stackexchange.com/a/11131