I found a great tool to create a Windows 8.1 Portable USB drive or
external HDD. This tutorial is about installing Windows 8.1 on a USB, not about Installing Windows 8.1 from a USB drive.
2. A 15 GB USB 3.0 or larger flash drive.
3. Access to a computer with Windows Operating system installed that can boot from a USB drive.
Requirements:
1. A Windows 8.1 ISO or Windows 8.1 Disc.2. A 15 GB USB 3.0 or larger flash drive.
3. Access to a computer with Windows Operating system installed that can boot from a USB drive.


