First, you have to decide on the type of ambient illumination you are going for. There seem to be a few styles that have become prominent, as ambient illumination gest more and more popular:
The Christmas tree look
Use those LED strips you got off Amazon and put them to use. Your retinas will definitely be burning and you will see individual hotspots for every LED on the strip. This will definitely be bright.
This will give you the best bang for your buck and will also be easy to accomplish. Results will be extremely poor, lighting wise.
Exposed Light Pipe Look
This is dramatically different from the Christmas tree look. It involves stuffing flexible plastic tubing in panel gaps and lighting it up with an LED at either end of the tubing.
There are many issues with this approach the biggest one being the terrible look during the day. And no, it will not be nearly as bright as all the over-exposed images you see on product pages. Not even close. However, this will be easier to accomplish than the Christmas tree look and it will probably be even cheaper.
Indirect Lighting Look
This is the OEM approach in more upscale vehicles, including Mercedes Benz. Unfortunately, this is also the most painful look to replicate but the results are well worth the pain.
These system work by having the light pipe, which is much thicker and better designed than the system mentioned above, built directly into the interior panels. LEDs are usually placed at either end of the pipe. The pipe itself is hidden and illuminates the panels below, giving it a soft, indirect illumination look. In other words, the light source is not directly visible.
The Best Approach
So what’s the best approach for my car? As usual, the answer depends on the project budget and the design of the interior car panels. The indirect pipe look can be accomplished in minutes. Will it be the best? No, but it will get you started.
Is it possible to retrofit the indirect illumination look into other cars? Absolutely. It will involve cutting up the interior panels retrofitting diffusion material or light pipe into the panels. This will be extremely time consuming and definitely not a budget friendly project.
You are also not stuck to using one system. Feel free to mix and match whatever would work best for your situation. The footwells are easily illuminated by an LED strip. If you can find a spot to hide some light pipe in a gap in your dashboard then why not? Be creative.
