(defun C:3DFtoPL(/ ss1 sl i)
(setq ss1 (ssget "X" (list (cons '0 "3DFACE"))))
(setq sl (sslength ss1))
(setq i 0)
(setvar "cmdecho" 0)
(while (< i sl)
(setq ent1 (entget (setq e1 (ssname ss1 i))))
(setq pt1 (cdr (assoc '10 ent1)))
(setq pt2 (cdr (assoc '11 ent1)))
(setq pt3 (cdr (assoc '12 ent1)))
(setq pt4 (cdr (assoc '13 ent1)))
; Plain 2D Polylines
;(command "PLINE" pt1 pt2 pt3)
; 3dPolylines ->
(command "3DPOLY" pt1 pt2 pt3)
(if (/= pt3 pt4) (command pt4 "c") (command "c") )
(entdel e1)
(setq i (1+ i))
)
(setvar "cmdecho" 1)
(setq ss1 nil)
(princ)
)