Sheet metal: Flange miter with angle..
While far from ideal, you can create a flange and use the Move/Copy tool to rotate the edge of the created flange. Suppress that flange and create the next one and rotate its sides and so on.
If you choose to do this I would definitely wait until you're as certain as possible that it won't change.
If you extend each of those flanges to the full length of the edge, you can use a sketch to Extrude|Cut the corners to fit.
ETFrench
daniel_lyall wrote:
After you make the first flange then after on a attached flange on the right side of the flange dialog is the full edge drop down, in there you have the option to change the flange width a few different ways.
If the bottom is going to be flat make it as one part not two different flanges so you can bring them up as one then when you do the horizontal flange do it the same way as one then it works how you wont it to, after that you use the extrude command or the move command to move a face, or lay it flat and sketch what you wont to cut out then extrude cut to cut it out..
You are telling basics. But this doesn`t work...
If I extrude them all at the same time, they just stick together...
TheCADWhisperer wrote:
There is a robust (fairly simple), fully parametric technique.
If I find the time, I will present a solution.
Hint: Hybrid surface/solid modeling with end result of valid sheet metal folded and flat pattern.
I`ll be waiting for your technique as hard as possible, because that`s the most important feature in my practice.
How can I sleep now, knowing that there`s a solution?
Hope you`ll find time sometimes, thank you! 
I was referring to using the Move/Copy tool to grab the edge face and rotate it. To avoid messing up the seam between vertical faces, it's best to split the side face before changing the angle. This is not an ideal solution but will give you a part that unfolds.
