;TIP589.LSP   Invisible 3D Face Edges   (c)1990 Paul Sherwood
(defun c:inviface ()
  (setvar "cmdecho" 0)
  (setq ALL nil)
  (initget 1 "Y y N n")
  (setq ALL (getkword
    "\nAll 3D faces on layer to be invisible? (Y/N):"))
  (setq ALL (strcase ALL))
  (if (= ALL "Y")
    (progn  ;select by layer
     (setq INLAY (strcase (getstring "Enter layer name: ")))
     (setq FACES (ssget "X" (list (cons 0 "3DFACE")
       (cons 8 INLAY))))
     (setq INDX (sslength FACES))
    )
    (progn  ;select by picking
      (prompt "Pick 3D faces...")
      (setq FACES (ssget)
            INDX  (sslength FACES)
      )
    )
  )
  (prompt "\nworking")
  (while (> INDX 0)
   (prompt "a")
   (setq ASLIST (ssname FACES (1- INDX))
         ENTITY (entget ASLIST)
   )
   (while (= (cdr (assoc 0 ENTITY)) "ENTITY")
    (progn
      (prompt "b")
      (setq ENTITY (subst (cons 70 15)(assoc 70 ENTITY) ENTITY)
            INDX   (1- INDX)
      )
      (entmod ENTITY)
    )
    (setq INDX (1- INDX))
   )
  )
  (princ)
)