Eggshell is used for it. You remove the top of the egg carefully, then use the egg itself as you like, wash the eggshell properly and let it dry. Collect as many eggshels as you need, then put something you like inside (vegetables, garden stuff, ham, anything you like and think will go well together) and pour in the broth (the one is cooked for холодец usually).
293_0566bll_5990_b.jpg