The rough cut on the ABS sheet doesn't look too bad, actually, until you look closely, but that rough cut is not visible, so no real failure. Do the grooves inside the lip snap-fit to anything on the cylinder outer wall, like threads (assuming the base of the bottle jack was screw-on type)? Great adaptation of the travel mug. I may have to copy that, use up an old tractor hydraulic cylinder left to die decades ago in the dirt on my farm. I find many uses for ABS and several other polymers - adds a good look to yours. I really like the idea of the heft. I constantly reach for coffee without really looking where my hand is going and it seems I bump the mug just enough to knock it off kilter...which is why ceramic mugs are banned from my workshop.I hate when I do that.