(defun C:SPIRAL (/ #DIAMETER #PITCH)
 (setq #DIAMETER (getreal "\nDiameter: "))
 (setq #PITCH (getreal "\nPitch: "))
 (setq #COILS (getint "\nNumber of coils: "))
 (setq #POINT-0 (getpoint "\nCenterpoint: "))
 (setq #RESOLUTION 16)
 (setq #RADIUS (* #DIAMETER 0.5))
 (setq #ANGLE-DELTA (/ (* 2 pi) #RESOLUTION))
 (setq #ANGLE 0.0)
 (setq #SEGMENTS (* #COILS #RESOLUTION))
 (setq #Z-DELTA (/ #PITCH #RESOLUTION))
 (setq #Z 0.0)
 (setq #LIST nil)
 (repeat #SEGMENTS
  (setq #POINT-1 (polar #POINT-0 #ANGLE #RADIUS))
  (setq #POINT-1 (list (car #POINT-1)
                       (cadr #POINT-1)
                       (+ (caddr #POINT-1) #Z)))
  (setq #LIST (cons #POINT-1 #LIST))
  (setq #ANGLE (+ #ANGLE #ANGLE-DELTA))
  (setq #Z (+ #Z #Z-DELTA))
  )
 (setq #LIST (reverse #LIST))
 (command "_.spline")
 (foreach #POINT #LIST (command #POINT))
 (command "" "" "")
 )

    Source: geocities.com/wpsmoke/acadalisptrng/scott_hull

               ( geocities.com/wpsmoke/acadalisptrng)                   ( geocities.com/wpsmoke)