Generate random MAC addresses with your choice of separator and case. Locally-administered, unicast.
A Media Access Control address is a 48-bit hardware identifier for a network interface, usually shown as six pairs of hex digits like 02:1A:2B:3C:4D:5E.
Yes. They're generated as locally-administered (the second bit of the first byte is set) and unicast, the range reserved for local use, so they won't clash with manufacturer-assigned addresses.
Cisco-style notation groups the address into three blocks of four hex digits, like 021a.2b3c.4d5e.