WinToUSB

WinToUSB is a utility that allows you to install and run the Windows operating system on a USB hard drive or USB flash drive, using an ISO image or CD/DVD drive as the installation source. In the latest version, you can clone an existing Windows operating system (Windows 7 or later) to a USB drive as a Windows To Go workspace. WinToUSB also supports creating bootable WinPE USB disk, it can help you transfer WinPE content to USB disk and make a bootable disk.