That's cool. Punch holes in these printouts, glue different layers together, add some extra ink into the holes for conductive connections between layers ("vias" [0]) and you can make multi-layer boards easily.
Surprisingly, silicone rubber has a dielectric constant between 2 and 4 [1], which is pretty close to FR-4's 4.4. So maybe it isn't impossible?
[1]https://res.mdpi.com/d_attachment/polymers/polymers-09-00533...
FR4 boards are built with woven fibers, and you can get measurable differences depending on how tight the weave pattern is, or the angle of your transmission line relative to the weave pattern. Given that paper is not woven, I’d expect a lot more dispersion than on cheap PCBs.
That said, with a good enough process able to press the paper + resin stack reliably, you could possibly get something usable.