do you have a good source for the Cycloaliphatic epoxy. I am also in the desert and have the same sun problems you have. Thinking of giving this stuff a shot.
They call it 300/21, and it is similar to what I have been using. If it is ok outside on an AZ pool deck it will be fine in a taillight. Aeromarine has the proper colorant for this material as well
Be aware that this stuff is epoxy. It bonds to things very well. It will even bond to a silicone mould sometimes. Use a release agent like Sprayon S00311 on any mould. Be patient. At 75f this stuff is thin, and you can pour it easily. Let it cure for 24 hours before demolding.
