5. Broken plate:

It is customary to use a broken plate for the spilling of the wine by the recital of the Makos during the Seder. One should verify that a broken plate is available and if not then one can simply chip a plastic bowl before Yom Tov. It is forbidden to break a vessel on Yom Tov for this purpose.[1]

[1] See Admur 314:1; 313:19