The pen is a bit on the heavy side, but not crazy so. I just measured a Lignum Vitae Sierra at 41g and this is 53g.
The surface is just as it came off the shelf at Lowes, the only smoothing is where I turned it to fit the Sierra hardware.
The challange is that re-bar is not very uniform in diameter, and the diameter of the metal inside the diamonds is only about 0.050 larger than the Sierra kit, so it is a bit tricky to drill centered and strait. I drilled on the lathe, and got the drill to enter strait, but it was off by at least 0.010 on exit. I will probably try a milling machine next time. The diamond pattern on the re-bar makes gripping it strait a challange.
For it's intended recipient, I attempted no surface treatment.
Possibilities for treatment include bead blasting or pickling prior to perhapse clear powder coat or black oxide (hot not cold). If one wanted to do black oxide you would have to do a lot of them to make it worth the price or just toss it in with other stuff you are having black oxide done to.
I was struggling to get a decent additional photo. Unfortunetely I just have a point and shoot, my good manual focus super macro setup is film not digital.
Here is the best I could get focus on