Calculating the resistance of curved resistive paste deposits
The calculation can be done numerically. It's a relatively simple 2-dimensional problem. It's likely not worth it unless you are already up to speed on the software, in which case you'd not be asking the question.
Make a scale model and measure it. If you print the model, print a simple resistor at the same time to establish the sheet resistivity. You could also use any material of known resistivity and thickness or known sheet resistance, but the classic approach is to use Teledeltos paper (around 2k-6k\$\Omega/\square\$), silver paint and an Xacto knife. It's fairly hard to source these days (mostly seems to come from the UK). Bob Pease (RIP) wrote an article on using it.
There's probably no point in getting too picky about the results since you are unlikely to be able to control the thickness and resistivity all that well. Printing that fine a line will likely result in artifacts at the edges from the screen mesh, if screen printing is used. Those artifacts will not scale. It will be sensitive to squeegee pressure, speed and angle (and a bunch of other things!) if printed with a screen or stencil. Other than that, the resistance should be the same for the same sheet resistance whether you make it size-as or 10:1.
Probably +/-20% would be a good result in a non-production situation with limited control of the variables. I would not be surprised if it was much worse.
My rough seat-of-the-pants ballpark guesstimate is that if you take the length between 1/4 and 1/3 of the way from the inside to the outside you'll get an answer that's maybe close enough. So around \$R_S\cdot\pi\cdot (0.3 + 0.2a)/0.2\$ where 0.25 &lt; a &lt; 0.33 or around 112\$\Omega\$ for the section shown for 25um (0.001&quot;) thick and 20\$\Omega/\square\$ if I did the sums correctly.
You should pay attention to the watt density as well as the resistance.