Trying to create a Windows 10 USB stick installer using an official Microsoft ISO on Mac OS X 10.11.6 seems to be hard work.

tl;dr: Using Rufus inside a Windows XP VM works

I happened to have one lying around, and passing the USB stick device through to the XP VM worked perfectly.

Methods that don't work:

• sudo dd if=win10.iso of=/dev/rdisk3s1 bs=1m
• unetbootin (the USB stick boots, but Windows 10 isn't an option in the list)