In 2010, as a birthday present for my girlfriend, I made her a set of knitting needles in the machine shop. I used .250″ OD x .125″ wall stainless tubing for the body of the needles, and machined press-fit tips and ends. As you can see, my press-fitting skills still left something to be desired – it took a couple of tries to get the tips to fit snugly.
Once the needles were machined, assembled and polished, I engraved the ends of the needles with a Dremel tool and a variety of bits (mostly diamond needle bits). This is not something I would recommend trying – it took forever to carve the stainless steel, and I went through a small fortune in bits doing it. If anyone knows a better way to carve stainless with a Dremel, I’d love to hear it.
Finally: to be perfectly clear, these knitting needles aren’t intended for self-defense/combat/whatever – they just happen to be long, and pointy, and made of steel. I’m pretty sure they’re not okay to take on an airplane, though.