What I managed to do is this (using standard 18° step) :
But, that's not exactly what I want to do. And, besides, some bricks don't really connect.
I actually managed, using hinge tool for hours, to make bricks connect with an angle close to 12°. But I have problems over the third level of bricks. If you look at the blue bricks, you can notice that the angle is 0° between the 3rd and the 4th level (for example) but just for one or two of the 10 2x1 bricks. Moreover, this is only possible using clone tool of your 3 first levels.