Ground it and what else would you do to modify the steel trash can to bend the magnetic waves? Change its shape?
Right Angles do work the best.
A Iron Box like a safe is actually one of the best shapes (if completely sealed), the problem is you have to align it to the poles of the blast to get the optimal protection.
since that is impracticable, the best is to either be able to electrolytically align the cube or have a sphere with many points of entry and exit for the magnetic waves.
Also, if you want to get some real basic
You want a point in which the waves enter and leave. If you can’t do a sphere, a cylinder is the next best.
You have to have it completely sealed with ferrous metal though.
For the galvanized garbage can (which I wouldn’t use due to hidden defects), I would first turn it upside down. Put your stuff on the lid instead of down inside the bottom when you are ready to close it up.
Next, strip the galvanized coating off the lead and the lip of the can so you get bare metal to bare metal.
Put in a ground strip to the inside of the can to the lid. Make sure not to create a hole in the metal. Copper Brad Grounding wire works the best.
Follow all the other instructions on the blog accept substitute flame proof lagging material for the cardboard.
Put your stuff into mylar bags with desiccant, now weld it up. Yes, Weld it shut.
Put the entire can at least 6” deep in the ground and use a copper grounding stake to ground the entire thing.
If an EMP happens, cut open the can and enjoy your working electronics. (assuming you aren’t close enough to get hit by higher energies)
For more examples of this: http://www.coolmagnetman.com/magshield.htm
Remember, you need multiple shielding for emp. Different energies require different materials and techniques.