How to choose LED lenses
What you're looking for is also called a "light pipe" or "light guide."  If you're designing a product for high volume production, the mechanical design team can create custom ones.  They're just little pieces of clear plastic that go between an LED on the main circuit board and the edge of the product case.  Most off-the-shelf ones are designed for generic high-volume uses where custom mechanical design doesn't add much to the product value, like an array of lights on the front of rackmount equipment.  It seems unlikely you'd find exactly what you're looking for since it sounds like an unusual scheme.  If you're a hobbyist you might be able to cut a piece of Plexiglas, or custom mold something that works reasonably well out of epoxy.  The optical properties of the material won't be the same but it might work well enough.