Print 2 of these and mount one on top of the other on anything round on your bicycle. Fasten with a few zip ties (or even rubber bands) as shown in the pics.
Go find the cheapest LED flashlight that you can and strap it to the top. I've seen LED flashlights at the grocery store and pharmacy for less than $3. Voila!
I am always working on new stuff to print. If you interested in being the first to know when I release something new, then check out https://www.arsenalproducts.com/3d-printing