Just thought I would share some resources. You can use the following websites as a guide for your builds.

This site will provide you the diameter of your drill bit:
Drill Bit Sizes & Conversions Table | Ballenger Motorsports

Which you can then input into this site (along with other information) to get a good idea on what you need to do:
Steam Engine | Vaping related calculators

I highly recommend Wire Gauge Drill Bits as opposed to Fractional or Millimeter, because of how much more precise you can get, if you juggle the diameters around with the target resistance you can virtually build anything to very precise specifications, for anyone else sharing my OCD.