Self center jig

The center hole will fit the pencil tight (use rubber hammer to push it in). The anchor holes are 5/16 or whatever smaller. Please make sure the nut on both sides line up with the same position for more accuracy.

Some features can be improved:

- 3D printing the anchor rode instead of using nut and bolt.
- Pencil can be replaced with nail if you want more visible on dark wood and accuracy (thinner line).