dd to make a clone of your drive.
dd will make a bit for bit copy (meaning an exact copy) of the drive; so whatever you have on the source, it will be exactly replicated on the target. One caveat is that your target must be the same size or larger than the source.
Before you begin you will need to know what your disk identifiers are. Open Terminal and type
diskutil list to get a listing of all your connected devices. Find the drive attached to USB and make a note of it's identifier; it will be
X is some integer.
Make an image of the source drive. Using
dd make an image and save it to your Desktop to be reused for each clone. I will be using
disk5 and your
Desktop as examples. Be sure to change these values to whatever is specific to your environment.
sudo dd if=/dev/rdisk5 of=~/Desktop/source.img bs=1m
This copy process may take a while depending on how large your drive is and how fast your USB connection is (USB 2.0 or 3.0). Once the process has finished, remove your USB source disk and replace it with a target
Create the target from the image.
sudo dd if=~/Desktop/source.img of=/dev/rdisk5 bs=1m
Once that has finished, remove the newly created disk and install in your Mac
Repeat Step 2 as necessary
You will notice that I used the disk identifier
/dev/rdisk; this is not a typo This allows you to access the "raw" device (direct access to the actual disk itself). This enables faster access to the device.
Recommendation: IMO, I wouldn't use a MacBook Pro to do the imaging (steps 2 & 3). Personally, I would use a desktop PC (Mac Mini works as well) and connect the drive to the secondary SATA port; it will make the process go much, much faster. Using a cheap PC with FreeBSD or Linux (I prefer FreeBSD), you can use the exact same
dd command to image the drive.