I’d like the wide bit at the left to be aligned with the ground, and the pointy bit aligned to the +Z axis.
(Blue-skying here…) I imagine it will involve:
getting the 3DC to the midpoint based on the “bottom”, and
aligning the rotation of the 3dC to the pointy top, then
moving the Object’s origin to the 3DC, and then
zeroing out the object’s rotation,
or something like that. Now I need to find out how to do that in Blender.
1 is easy, 2 I don’t know, 3 is easy, 4 is easy. So, really, just #2.
EDIT1: I can get the 3Dcursor placed and rotated (it seems) by making a temporary Face on my desired plane (“Snap Cursor to Selected”), but when I then Snap the object’s origin to the 3DC I can’t seem to get the Object’s origin to coincide – I’m not sure if that’s because it didn’t work or that I’m not displaying the Object’s origin correctly, that is, the Gizmo doesn’t seem to be aligned with the Selected face. My feeling is the transformation should be Local, but again, it doesn’t seem to be correct.
Yeah, that part is easy, the question is how to rotate the object to align with something else. (Local origin >position< is easy, not so sure about local origin orientation.)
I know the capability is there, it’s just the workflow escapes me (yet again).
This of course is always guessing, because the original rotation is unknown/lost.
…
But now looking at @rigoletto’s file i remember the align view trick, which he used (?) but didn’t mention ?? Okay select the 16 vertex base n-gon not seen in your image. Then align view to active top, switch to Oject mode and add a plane but with orientation (AddPlane properties Align: change to View). Now parent your object to plane ( like in the blend). Now the rotation of the plane cane be selected (all 3 at once then type 0) now … dam’ while i’m typing this @Ztreem is posting a video… oh interesting, too
But a really cool feature would be to use the normal directly… Wait there was something about orientation in 2.79 with local global view … and self defined …
Edit: A yes in 2.9 there is a plussign in Transform orientation but this only is used in edit mode of this object …