This homemade transfer punch worked for me for drilling a panel to match the mounting plate of an instrument. The plate already had nutplates attached to it.
My matched-hole punches are in fractional sizes, so they didn’t fit. However, I found a number drill bit that was a very good fit. I sent the panel’s owner out to the hardware store to buy me a replacement bit, and I cut the flutes off my bit with a Dremel cutoff disk. This left me with a short smooth stub, about an inch long. That went into the drill press, and I put a shallow point on it.
Presto! A custom match-drill punch.
Since I used a very small tap hammer to make the punch marks (the owner had the instrument in place while I made the marks, and I didn’t want to jar it with a larger hammer), I had to go over these rather shallow punch marks with a deeper punch, but that was no big deal. Then with the locations very well defined, the owner drilled the holes.
The mounting plate fit perfectly.