V sapped LED diffuser panels, stick any strip LED  inside the V shaped panel.

The diffuser can be printed with single layer with clear or white filament that can make the light dispersion very different. reduces galyer and provide a nice diffused light.

print multiple panel and stick them with super glue to extend the length and scale down on one axis to shorten the length. 

at the 90 degg. corner cut the diffuser using a pair of seizors by sliding from both side and mark a arc to cut latter on.