Every Windows 7 was equipped with Windows PE (Winre) as a recovery tool that can be accessed from the install DVD, recovery folder or system repair CD.
All of those WinRE images are the same except that they start with a different shell.
Windows 7 has DISM to mount/unmount WIM images, these resources (winRE and DISM) can be used to build a custom Windows 7 PE without downloading WAIK.
Tsetya made a batch command script to build custom Windows 7 PE using winRE images, mount WIM's using DISM, add additional file/registry, save WIM images and create bootable UFD using Diskpart to be used
with Windows 7 PE.
This script also has an additional task to create a back up of the installed Windows 7 so that you can use UFD to boot your current windows 7.
Hope you have fun running your Windows 7 from the pendisk!