CAD tip # 13049:

For example, let's imagine letters of text written along an arc, and we now want to tilt each of these letters along its lower baseline.

The following code in LISP (AutoLISP) will help us:

(defun C:ROT3D1 ( / ss i)
 (princ "\nSelect objects to rotate individually in 3D")
 (setq ss (ssget) i 0)
 (while (< i (sslength ss))
  (setq ent (ssname ss i))
  (command "_UCS" "_obj" ent)
  (command "_ROTATE3D" ent "" "_X" "" 90.0)
  (command "_UCS" "_P")
  (setq i (1+ i))
 );while
)

Save it to a text .LSP file, then load the file into your AutoCAD using APPLOAD (or drag and drop it with your mouse) and type the ROT3D1 command. Select the individual letter objects and they will be rotated 90° along their local object X-axis.

See an example: