These are all of the pieces of the jig. I used scrap piece of aluminum and squared up the edges. The big slot allows the brad point drill to pass through the drill blank. The aluminum plate is thick enough that it can be mounted directly to the table and still allow the drill to not touch when it just breaks through the pen blank. Bigger...

The purple pieces are UHMW, which I got in a bulk bag from Lee Valley. The holes are all countersunk so that they don't interfere with anything. The horizontal slots are for mounting to the table. This scheme will work with either the mill tooling plate, or with the slots. Bigger...

This is the assembled jig. Bigger...

This is how the jig is used to drill holes in the pen blank. Bigger...

Here's a dimesioned drawing of the pen drilling jig. Also available in PDF and Rhino formats. Bigger...