Boot Raspberry Pi 3 from USB memory stick

To boot from USB I need to set USB booting bit to 1:

program_usb_boot_mode=1

This is a one-time change and it cannot be undone. Once this is set it will still primary boot from MicroSD card and if the MicroSD card slot is not usable it will try to boot via USB port.

This is my favourite configuration so far for Raspberry Pi 3 system:

Of course proper cooling is needed: