Both, I think. Iirc the outside was a plastic shell that clipped to the metal toaster. It caught fire when the overfilled tortilla started dripping cheese onto the heating coil.
I don't know if I was more upset about the fire, losing a toaster, or not having a succulent quesadilla dinner.
Do not do this. Toasters are not made to be used sideways. At best you’ll melt the probably plastic sides of your toaster, at worse you’ll burn your house down.