I try to make a 100% custom rig system based on stretching bones, and I kind of manage to do everything correctly, BUT, and that's a problem I've met for years on Blender, I can't find a way to make a proper Arm twist bone.
What I want, in fact, is that the hand controller is just parented from the Root controller. Here, I know why I have this problem. On this test I made and I show below, my hand is oriented to the right. Though, on this pose, it is oriented to the left and rotation axis reaches approximately 180°. And thank's to how bones work on Blender, the axis then switch to 179° to -179° instead of 181° when I add 2 more degrees.
Though, even if I understood the origin of the problem, I'm unable to find any way to fix it.
Of course, I searched for some tutorials on YouTube and else, but each tutorial I found either ignores the problem of the arm twist (so the tutorial is incomplete), or do as if the rig is done and correct while it would give the same result as me with some complex poses.
Ah, and I also know about rigify, but the rigging it's suggesting is too much complex for what I intend to do.
You can see the result here to understand better what I mean (I made an arm very quick just to make some test):
Can any of you help me to finally find a way to fix this issue?