on ebay look for side glow fiber optics. however the light will be dim/etheral, and you'll need a bright led at the ends to make it glow.
EL wire will be much brighter, and is flexible and easy to play with. it is fragile so it'll break if you flex it too much like on a worn fabric, after someuse. most damage comes where it is soldered to wires, but that's easy to fix. some breakage can happen when the el itself breaks and you can end up with dark sections or weird blobs of on vs off sections.
you can buy el from 1.6mm to 5mm (1/2cm). different colors will have different brightness because of tech. lime green is brightest.
it's very cheap on ebay, unless you need super bright 3rd gen el.
for a sculpture el is likely good.
you could also make your sculpture in acrylic, and just put leds on the sides or bottom to have it glow. No need for fiber optics, unless you want to use it to distribute the lights.