Roman Leather Lamellae Scales from Karanis, Egypt

[Urselius]

"Made from earthenware, bronze, or iron, the clibanus, often preheated, was used to cook not only bread but also meat. Literary and archaeological evidence from places like Cosa, Pompeii, and Rome show that the clibanus was round or domed-shaped and wider at the bottom than at the top."

Ancient Food Technology - Page 368
Robert Irvin Curtis - 2001

Not a big leap of imagination from a bronze or iron box to a cuirass of some sort. Though it does suggest plate rather than scale or mail.

A corrupt official used a bathhouse oven to bake Belisarius' buccellum for his Vandal expedition. The biscuit was only partly baked and led to the (probably ergotic) poisoning of many soldiers.