It's why we can trace the film or paper curves
making a precise argentic step tablet is not an easy work and it's why this
little piece of film is expensive, it's not just a sheet of film.
I have never used Arista film so I do not know whether it is possible to
repeat a step wedge on it or or not but I am tempted to doubt it as very
few films will give the necessary range. One which will is FP4 . Try
developing it in Ilford's Universal developer at 1:9. Development time to
give that range will be about 2m 15s at 20 C but you well need to do tests
for both the exposure and development. You will also need to work in the
dark as this is a panchromatic film.
I am not suggesting that the accuracy will match that of the original step
wedge for these are essentially engineering standards, as Pascal says, on
which much money may depend. The results should be sufficient , however,
for most of our purposes.