This DIYer built his own Microwave HERF (high-energy radio frequency) gun by using parts from an old microwave oven. The electromagnetic gun works just like a normal microwave with a high energy source triggering a magnetron which produces microwave radiation at 2.45GHz. The targeting part is a waveguide made out of metal which directs the microwaves in one direction instead of letting them scatter.
If you have an old microwave around you could setup your own HERF gun with the help of the step-by step instructions. There’s also the video above. But as the instructions point out, don’t attempt a HERF gun without proper education and safety precautions.