(define-prefab foo ()
  ((node-a)
   (comp1 :test 1)
   (comp2 :test 2)
   ((node-b))
   ((node-c)
    (comp1 :test 3)
    ((node-d)
     (comp1 :test 4)
     (comp2 :test 5))))
  ((node-e)
   (comp1 :test 6)))

;; =>

(copy-tree `(foo () ()
                 ((node-a)
                  (comp1 :test ,(lambda () 1))
                  (comp2 :test ,(lambda () 2))
                  ((node-b))
                  ((node-c)
                   (comp1 :test ,(lambda () 3))
                   ((node-d)
                    (comp1 :test ,(lambda () 4))
                    (comp2 :test ,(lambda () 5)))))
                 ((node-e)
                  (comp1 :test ,(lambda () 6)))))