The Wordsmith's Forge

they would only shatter if they came into contact with a significantly rigid and hard surface with enough force and angle(skidding against the wall or onto the floor from a height)If Steve is actually dealing them like cards or tossing them like his shield to land on a specific point, then he is calculating the mass and velocity of the individual trivets and applying the correct rotational force so that they glide on a cushion of air and come to rest on the table gently.