This is the final look of the bag.It is an ordinary backpack bought from outdoor clothes shop.($7)
There are 3 small very strong magnets placed downside of the bag.
This way you can easily take apart your tank bag as a backpack.

Step 1: Gathering Tools

What you need

1-A backpack which is not bigger than your tank.
2-Very strong magnets, you need 3 pieces and the surfaces must be clean and polish.
3-Tools for needlework

Step 2: Removing Magnets From the Harddrives

Remove the upper cap of the drive,(1)
Remove disk plates
Take out two chassis, (3)
Remove the magnet core from the chassis (4)
And finally you have the strong small magnets.
There are two per drive.

Step 3:

Cut small holes for every magnet and put them in then do the needlework for three of them.
Shape is like beam, and placed the rounded part to the corner of the bag.
Test 3 magnets after this step with your fingers.
They have to be really polish and soft,
!!!!be careful non polish magnet can scratch your tank badly!!!!

All done! Test it on your tank!