If you want to download an Exel spreadsheet that will calculate fret locations in inches or MM, here is the link. It is a protected sheet, but there is no password should you want to modify if.
The problem constructing fret positions with compass and rule is the fact that typically you start with the desired scale length A-B and you calculate A-C as 1/18 of A-B. To give an example, for a scale length of 25" or 63.5cm you end up with 1.39" or 3.53cm. With a slight error marking A-C on paper, you will end up with a scale length somewhat different as intended when you calculate the final scale length as twice the distance from the nut to the 12th fret, even if you work very carefully with a pair of dividers / a compass with two metal points, I don't know the correct term. So try a couple of times until you get the wanted scale length.
another problem with compass and rule is cumulative error... thickness of the pencil line, placement of the compass point, error in the ruler measureing AC, etc, because each point depends on the accuracy of the previous one...
you could have a 2% error in laying out AC, another 2% error in AD, another 2% in DE, another 2% in DF, ad-nauseum
and when you get to the 12th fret you are off by 24%.
JL hits the most important point in fret layout accuracy. Cumulative error is unavoidable in a point to point measurement system. And, it is a killer. I think just about all instruction on measuring stresses making all measurements from a single starting point to avoid (or minimize) the cumulative error.
If all fret locations are measured from the nut (or nut line) and measured in MM instead of fractions of an inch, it is entirely possible to locate each fret center within about 1/3 MM (or about 0.013"). Medium/medium frets are 2 mm wide so the crown of the fret is greater than the possible placement error.
I usually mark fret locations by taping a stainless steel scale (mm side) to the fret board, the use a sharp scribe to make a small prick for each fret location. This provides a very small mark to work from.
A good fret saw jig holds things square while actually cutting slots and the scribe dots provide the smallest possible mark to align to.
The only other thing I suggest for fret accuracy is to step away from the job after you've marked all the frets, then to back and check each mark one final time before cutting (measure twice, cut once............)
As to my experience, working with a compass with two metal points, an error of 24% at the 12th fret, is theory: my last example, for a scale length of 23.5" or 59.7cm: first try 62.3cm, second 58.1cm, third 60.0cm, with an error of 0.5%. Sure, working with a fret scale rule or a fret calculator is far more practical, but why use hightech to build a simple instrument... It's a good experience to have it tried some day.