This photo shows how our omniwheels were abused by vigorous physical contact during the 2006 Pacific Northwest Regional in Portland, OR. We did not shy away from the contact and are happy with how the wheels survived.
They’re constructed from a laser-cut delrin core that acts as a substrate between two 1/8" Al plates. The plates bent on several occasions and I’m certain the delrin is cracked, but the wheels did not ever fail. The rollers are EPDM rollers from AndyMark.