Okay, so I'm ICP level on magnets but let's consider the humble Rail Gun as our go-to elextro magnetic weapon cause thats the one I know about. Can't help but notice they have a big giant rail. And I'm pretty sure, even though my level of knowledge here is pretty minimal, someone who knows science facts good chime in plz causenid love.to be confirmed or corrected here but to get something up to a remotely bullet like speed with a magnet would either take both way more power thsn those batteries are gonna give ya and also it takes a big magnetized barrel to get them up to speed. Overall don't try to make this gun. It won't work cause we don't know how it works and if there is an explosive element it will just fill apart. Make a pvc blunderbuss, the true Proletarian weapon. If it fits in the tube you can shoot it and if you don't know how to gunpowder you can use cooking oil or hairspray as a propellant, you won't fo much damage unless you know how to build it good but it's fun and educational about rocket science and whatever to play with using a slightly more than reasonable degree of safety precautions and testing. I advice living in the country for this because you're just kinda allowed to do that outt there.

IIRC it used homemade black powder, there was a giant fucking cloud of smoke after he fired.