Step 5: Drilling A Line Or Grid
1) Remove any dust or drill shavings from the area.
2) Figure out how many cards you need to space your holes (center to center). For my example 3 of my business cards gives me 3/64" (1.2mm) distance.
3) Count out that many cards and put them between the jig and the drilling subject.
4) Drill your next hole.
5) Clean up your drill shavings.
6) Repeat steps 3,4 and 5 by adding layers of cards and drilling until you have as many in your row as you need. Be sure not to miscount the cards. (I did this more than once during practice and it will throw off your spacing and can cause spontaneous face palm.)
If you're just doing a line, then you're done!
If you want a grid, you need to make another line, offset from the first. Repeat the steps above, but also put cards at right angles to the first set. This will offset your material in two directions.
For advanced users you can draw a pattern using different numbers of cards and drill bit sizes. Like this amazing project, only smaller.
To do this at a larger scale size everything up and use sheets of plywood or square doweling as spacers. It makes the whole thing easier since you don't have to worry about sawdust or your drill press moving fractions of a millimeter.
Anything unclear? Ask in the comments and I'll try to help.