Not so easy to bore a hole. You can buy tubing but it's difficult to find the correct ID for the tap. Also hard to tap it straight. They sell "bungs" that are weld-on threaded ends, I think they run about $15ea and work real well. I've made rods by welding long nuts to the ends, or a regular nut in light duty applications. They also sell rod ends that are solid (no ball) if you don’t need side to side movement.
Another really good option is use urethane bushings to make custom ends. I’ve used generic bushings from the local off-road shop, and speedwaymotors.com has some really stiff urethane bushings.