Add some diffusion to your led strips with clear PLA. Play around with different infills for desired effects. I chose 60% "Gyroid" infill in Cura.
Scale the Z axis to your desired length. Photos show the unmodified 10mm stl and scaled 45mm version.
Fusion 360 file included!
EDIT 11/18/18: Added a version that grips a bit tighter, and versions with a closed back.
3d Solutec PLA