Step 1 - 8" "Flex LED" retails for $14.99 at parts store

Step 2 - Cut scrap piece of metal to fit into housing. I used aluminum that I bought at TSC for $5 for a 4 ft length.
Step 3 - trim metal to fit housing, then glue into place. tape lights to metal

Step 4 - put housing and lens back together
Step 5 - test to make sure no wires are pinched.

Step 6 - install lens in trunk and splice into wiring for stock 3rd brake light. Black is ground, black with white stripe is positive.

.. and that's it.