Make blocks out of custom symbols

I do mostly graphic symbols from lisp (2D springs, hole centers,
centerlines, etc.) How can I have my progs create a block out of my symbols
? I want the finished product to be a single object, not just a bunch a
lines. Should I create a temporary layer ? Or can I (cons (entget (car
(entlast)))) my way through it ? Here's an example of what I do:
(DEFUN c:2dspring ()
(SETVAR "cmdecho" 0)
(SETQ dia (GETREAL "\nSpring diameter : ")
lon (GETREAL "\nSpring length : ")
spir (GETINT "\nNumber of spires: ")
p1 (GETPOINT "\nInsertion point : ")
p2 (GETPOINT p1 "\nDirection : ")
dir (ANGLE p1 p2)
pt1 (POLAR p1 (+ dir (/ PI 2)) (/ dia 2))
pt2 (POLAR p1 (- dir (/ PI 2)) (/ dia 2))
sp (/ lon spir)
top (POLAR pt1 dir (/ sp 2))
bot (POLAR pt2 dir sp)
cen (LIST (/ (+ (CAR pt2) (CAR bot)) 2)
(/ (+ (CADR pt2) (CADR bot)) 2)
) ;_ END LIST
) ;_ END SETQ
(SETVAR "osmode" 0)
(COMMAND "_.pline" pt1 pt2 "")
(COMMAND "_.line"
(POLAR pt2 dir lon)
(POLAR pt1 dir lon)
""
) ;_ END COMMAND
(COMMAND "_.pline" pt2 top bot "") ; Creates 1 spire
(REPEAT (- spir 1) ; Repeats spires
(COMMAND "_.copy" (ENTLAST) "" pt2 bot)
(SETQ bot (POLAR pt2 dir sp)
spir (- spir 1)
) ;_ END SETQ
) ;_ END
(SETVAR "osmode" 439)
) ;_ END defun

Thanx a bunch

Dr Fleau