Since I'm not used to building with extrusion, I am a little overwhelmed with all the parts and possible combinations. Right now I'm thinking about differences in the corner brackets. When do you go for what bracket? The difference between Cast and Black Angle Corner brackets seem to be the price mostly, but they seem to work equally good. The Inside Hidden Corner Bracket and the L Bracket seem to be similar in that way too, with one having the advantage of being "hidden". Then there are the Joining Plates - especially the 90 Degree one . What are the mechanical differences between all these options? Besides connections where one bracket requires more space and might get in the way of something... Is one connection stronger than the others? Is it easier to get 90° corners right (or to square a build) with one of them? What else didn't I think about?