I now use the latest nvmutil, to set *random* MAC addresses on every laptop I sell!

I sell ThinkPads with coreboot and Debian Linux on my store: https://minifree.org

Coreboot replaces proprietary BIOS/UEFI boot firmware giving you more secure control of your boot experience.

I wrote nvmutil myself, recently, to replace an older tool that I wrote before. One of its main benefits is that it can set random MAC addresses, hardcoded in the flash. This is the "default" MAC address, for your NIC.