Stromer bikes use a special aluminum seat post adapter that has a beveled collar on the top edge (the last of the photo shows the original part). This beveled collar could also be used as a taillight.

The idea came from one of the mechanics at the bike repair shop where I have the service done for my Stromer each time. He asked me if I could make him a test model and how to illuminate the whole thing.

The model consists of three parts, a shaft, a base for the self-adhesive LED strip and a translucent cover. I have used transparent, red PETG.

The cold white LED strip I bought at Aliexpress: https://www.aliexpress.com/item/1005003218624665.html

Important: The plastic model shown here is a test implementation and not intended for effective use because for safe use, plastic is too weak as a seat post. Anyone who wants to use the model must make at least the shaft from aluminum for safety reasons.