[36] Now at that time the group-of-six bhikkhus used various kinds of bowl rests (pattamaṇḍala), made of gold and made of silver. People criticized, complained, and spread it about, … "just like householders who enjoy sensual pleasures" … They reported this matter to the Blessed One. … "Bhikkhus, various kinds of bowl rests are not to be used; whoever should use one commits an offence of wrong conduct (dukkaṭa). I allow, bhikkhus, two kinds of bowl rests: one made of tin (tipu) and one made of lead (sīsa)."
The thick bowl rests did not fit snugly against the bowl. They reported this matter to the Blessed One. "I allow, bhikkhus, that they be turned on a lathe." There were ridges. … "I allow, bhikkhus, that a makara-tooth pattern (makaradantaka) be cut."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.