I looked at the self centering vices for drilling pen blanks, but the problem I foresaw was that a lot of my pen blanks are cut green and then dry, so they are seldom straight, and or square......
I've seen various drilling vices on the net, and this is what I came up with.
The vice is just two pieces of 21mm thick MDF for the jaws, and one piece on the bottom that makes a base. There is a hinge on the right side, as I squeeze the vice closed with my left hand. I use one vicegrip c-clamp to hold the pen vice to the DP table, doing so gives me one pivot point, front to back, if you will, then the DP table is not locked to the DP column, so the table itself provides the left to right adjustment. I found it to work VERY well, I could line up the center of the blank for drilling quickly and easily.
In this pic, with the vicegrip removed, and the pen vice open, you can see the hinge, on the right, and the two clean out holes I made.
Here I'm drilling a blank, I'm just holding the vice closed with hand pressure.
Here you can see the bit of dust that has fallen into the vice, but because of the clean out holes, it is not in the way............
...............and after 20 or so blanks, all I had to do was give it a blast of compressed air and it was clean again.
Here is a blank that was not square at all, but the pen vice still worked fine!
I use the same pen vice when I mill the ends of the blanks after inserting the brass tubes, it works really well for that too.
Between the DIY pen press and this pen vice, my productivity has gone way up!