Using bootcamp on an external drive - Can you run it on different mac computers?
No, that will not work.


The windows drivers most likely will not be the same between Macs.
Windows will know you have changed computers and will not boot.


Also, have you investigated just how must effort is involved in installing Windows on an external drive? You can not use the normal Windows installer. You have to install Windows from the command line.

I suppose you could manually install all the drivers you would need for all the Macs you wish to boot from. Then you could run SysPrep to generalize before switching Macs, but this was not what Microsoft intended. Also, which Mac do you intent to be connected to when you Active the software? 

Windows does have a feature called Windows to Go, that can be used between computers, but I believe you will not have access to each computers internal drives. I also believe you need special hardware which comes at a premium price.

If you are still determined to try, then please report back your results.

If you get stuck at some point, please let me know. I might know how to proceed.

This is my answer to the question Is it possible to use Boot Camp with Windows 10 from an external HDD?. Of course, there are also many other opinions on how to succeed.

Below is some information on the Boot Camp Support Software.

Some the the websites are: Download Boot Camp Support Software 5.1.5769, Boot Camp Support Software 5.1.5640, Boot Camp Support Software 5.1.5621 and Boot Camp Support Software 4.0.4033. Those are for the older Macs. For the newer Macs, you can only download the Boot Camp Support Software by using the Boot Camp Assistant application. If you have to, you can use the Windows 7,  8 or 8.1 drivers to install Windows 10.

Each Mac is assigned only one unique Boot Camp Support Software package. When installing Windows, only the required drivers are installed. No Boot Camp Support Software package is an replacement or upgrade from any previous package. 

Updates for the Boot Camp Support Software is delivered by either Windows Update or by Apple Software Update. These updates will download after you have installed Windows.