Create ISO file from external HD

I have an external HD (bootable windows IDE) that I need to duplicate. I could order a drive duplicator but I only need a couple copies and it doesnt justify the expense. I was thinking I could burn an ISO file from the source, and burn the ISO on a blank drive.

On a mac, I could use the DD command
Ubuntu has a similar command tool built in
Windows has some 3rd party utilities, but I am not allowed/blocked from installing software on this PC

I made a bootable flash drive (Ubuntu) but I am locked out of the BIOS to change boot order and boot from a flash.

So I thought a portable app I could run from a flash would allow me to create an ISO file from a HD and then burn.

I saw a FOLDER 2 ISO app, and a CD 2 ISO app mentioned. Not sure if this will work for a bootable HD.

Any ideas of portable apps out there? I didnt see anything searching.

My only other idea is to remove the HD from the company laptop, force it to boot into ubuntu, and try that route

tia for any ideas