Found another paper. A much better one. Seems there's not much commercial fiber that has the right properties. These guys found a polymer,
"Geniomer 200 (Wacker AG, Germany), a polysiloxane-urea-copolymer with a polysiloxane content of > 90%. The polymer was used as supplied with no further treatment. The melt flow index (MFI) has measured 17.78 ± 0.52 g/10min (n = 3) at 1 kg and 170°C (Wacker datasheet: 170°C, 2.16 kg, 110-150 g/10min), and a melting temperature (Tm) of 171.31..."
So tentatively it looks very easy to 3D print with normal 3D printers after making into filament.
They then dipped in a refractive index polymer,
"...A low refractive index coating material (THV 220, n = 1.36; Dyneon, Germany) was later applied by dip coating the fibers in 5 wt% acetone solution (23°C). The coating thickness was calculated to 16 ± 3 µm by gravimetric analysis (n = 3). After the dip coating with THV polymer they lost their sticky behavior...."
The response in these, if they are not lying, is very good. 0-40 Newtons pressure. So fiber optic sensors not outmore complicated than just weaving a few off of amazon. It may well be that you could still use some cheap amazon fibers but...likely too stiff.