Just a cool idea I've been kicking around for about an hour, I'm trying to figure out how it could work. I'm considering doing this with backslpash tiles and maybe even some shower tiles.
Side illuminated fiber optic cable that's just the size of the gap between the tiles, then covering that in grout. I'd put it in every other grout line, because each line should illuminate tiles on both sides of the cable. Maybe if the cable is undersized, I can use some optical glue to attach the fiber to the glass
Using casting resin as a surrogate fiber. I saw a few people making their own fiber optic cables (for decoration quality, not data) by injecting it into a PVC tube. I figure if I attach all my tiles using ditra or some other membrane that'll prevent cracking, I can just "bridge" all the tiles using casting resin and then cover the resin with grout. Alternatively caulking or hot glue. Similarly, solid core 2mm fiber cut to the width of the tiles, glued face to face in the grout line between tiles. This would use the tiles as a pass-through. This would have to be vertically or vertically and horizontally as the brightness would definitely fade as it goes.
Regular fiber run along the sides of the tiles, glued or caulked down to the side of the tile. Maybe run it straight down the center of the grout line if the glue or silicone is conductive enough.
LEDs on the underside of the tiles. This will cast a shadow with the backing web, and this will cause a bright spot
I was considering drilling/grinding a 1mm hole in the back of the tiles, then securing a 1mm fiberoptic cable with optical glue. Except the hole would be ugly and clearly visible as the tiles get their colors from the backing. Drilling from the side would be time consuming and run the high risk of nicking one of the finish surfaces.
You guys have any other neat ideas on how to implement this, words of wisdom?