Recently I got a loaner car from Audi service. It was an A4 2017 model with a courtesy light feature under the doors, with the Audi logo. This gave me an idea to make something similar for my Miata.
eBay and Amazon have hundreds of options for such mini projectors. I found one on eBay for $8 for a pair of LED projectors for BMW.
These projectors have a removable film holder, which holds a 10mm circle film. This makes it possible to use any artwork design.
Using Adobe Illustrator I designed a few options with the Miata theme and made it on transparent high-resolution film with Gammatech service
Cutting such small circles is quite challenging, but I found on Etsy a hole puncher, which did this job perfectly
And here is the first test result:
Now, I need to figure out how to mount it. Mounting inside the door would be very cool, but it requires drilling. Second option: project on the footwell inside the car, which will be easier.
For the driver’s side, a 3D printed bracket will hang on the metal plate with a strip of Velcro. For the passenger side, a 3D printed mounting bracket can be attached by Velcro to the plastic cover. Bracket design published on thingiverse.com.
Here is how it looks now:

Ready to install

Connection with T-clamps
There is an instruction guide on the Miata forum, created by SirPete, on how to install the courtesy lights. I found it is much easier to connect with T clamps, from the bottom side of the connector… no need to unwrap any cables. To route wires from the driver side to the passenger side, I used plastic tubing, to protect the wires from rubbing against any metal parts in tight spaces.

Driver side
The Projectors will turn on when the door is open and go off when the door is closed. However, if the door is open for more than 2 minutes, they will blink a few times and shut off. I think it is a design feature to prevent overheating
There is noticeable distortion due to angled projection (see above photo). To correct this, I modified my slide designs: