I finished the plug and I think I figured out how to do the pictures. I turned the plug on the lathe. I made grooves for two o-rings (because... why not?). I also drilled and tapped a hole for a #6-32 bolt as a "handle." It took more than 5 1/2 pounds of force to get it in there. It shouldn't be coming out. I JB Welded the plug in afterwards. I tried to shove JB Weld in the groove like I was greasing a wheel bearing. I'll find out if it worked in a couple days when I get back to this project.