Small variable capacitors can be a pretty common component in homebrew radio projects, especially in antenna tuners. However, if you are like me, drilling the holes in a project box correctly can test your patience to the limit. I got tired of hacking up perfectly fine project boxes in the attempt of getting all three holes just right. Then the other day I saw a container in the trash that once had large muffins. For me, the clear plastic gave me a clear idea of what to do about getting perfectly spaced holes for variable capacitors every time. I did not need much of the clear plastic material so I just removed the lid.
I then cut the plastic down to a more manageable size.
Then I just placed the variable capacitor behind the plastic and now I could clearly see exactly where to drill the holes for the variable capacitor. 
Now drilling the holes in the perfect location was very easy. To test this little drill guide I went to work on a piece of scrap PCB board. I simply laid the clear plastic over the PCB board and used a center punch to mark the location of the holes.
For the large center hole, I used a 1/4 inch drill bit, and I used a 1/8 inch drill bit for the two satellite holes. Did it actually work and allow me to drill all three holes in the correct locations?
