Since you can make a cube as thin as you like, I'd say just use the cube and be done. Cube has no problems with visible side and invisible side either.
Matt did explain the way to set the plane vectors , you need to look up the sin and cos of the rotation angle you want ----
".... example of a 23 degree rotation about the Y axis needs to be worked out using some trigonometry, which is as follows:
Rotate Y = 23:
Edge vector a = cos(23), 0, -sin(23)
Edge vector b = sin(23), 0, cos(23)
Set your calculator to degrees to calculate the following:
sin(23) = 0.3907311285
cos(23) = 0.9205048535
Plug this into the Plane:
Edge vector a = 0.9205048535, 0, -0.3907311285
Edge vector b = 0.3907311285, 0, 0.9205048535
Note the minus sign.
BTW, the maths might look like I'm rotating in the opposite direction from what you'll see in text books, but I'm matching the Y rotation in other TG objects, which is supposed to match the heading on a compass.
Now, if you want to rotate on the X or Z axes, here's the trig for those:
Rotate X = 23:
Edge vector a = 1, 0, 0
Edge vector b = 0, sin(23), cos(23)
Rotate Z = 23:
Edge vector a = cos(23), -sin(23), 0
Edge vector b = 0, 0, 1
Matt"
