I too started wrapping coils on tge blue screwdriver. That shaft is 1.9 mm if memory serves.Yes, ohm readers are very cheap, AND, I found them to be about as accurate as a mod reading.
The point is to have several ways to check the ohms. Most read to the hundredths. When checking mine, I do a final trim to make sure all excess wire is trimmed, check that the screws are firmly tightened, coil is in the position that I want, and then fire the mod to get the reading. Then I try it on another.
coils are surprisingly easy to make. I started by using the little blue screwdriver, then drill bit, and now I have the coiller kit. I pretty much do 2.5 or 3 mm. Actually, I have come to the point that I do the same number of wraps each time. I don't need a calculator.
Once the coil is good, I wick it. A lot of different rebuildables require a sliiigghhhtly different wicking length. I just tend to use the same RTAs now. The kayfun-style deck is simple.
Building is relaxing and the FDA can't mess with the parts. I have not used a factory coil in 2ish years.
Anyway, it isn't hard at all. Good luck!
I have not used a pre made coil since testing the little Atty that comes with the Mini Volt.
For me 8 wraps 26 gauge around 2 mm Shaft and mg sweet spot .79-.84 ohms is there. I gave my ohm meter to a guy trying to build stupid low and using those HORRIBLE efest batteries. An explosive mod looking for a place to happen. This guy was wraping .2 ohm coils on the hammer mech mod. I was actually happy when his hammer stopped working and went with a regulated mod