• What is this thing I hear?

If you want to restore your car's headlights to their original shape yourself, the latest technique is to sand the headlights with various sandpaper grits and finish them off with a headlight atomizer cup, aka the “magic lantern”. You can have a look at this technique in the following video:

You can buy this “Headlight Restoration Kit” quite cheaply, but why do so if you have a 3D printer and can “make" it even cheaper?

• The kit on the market:

The kit consists of a metal cup that most of the time get's powered by a 12V car “cigarette lighter” plug, a funnel and a ”special" liquid.

If you dig further, you can easily discover that it's nothing more than a 12V car coffee mug heater, a homemade funnel and the liquid. What is this liquid you may ask?
Just plain old cheap acetone!

• The science:

“Plastic" headlights are made of PolyCarbonate (PC). Acetone has the ability to melt PC and ABS.
The method is to turn acetone into vapor and gently melt the upper layer of the headlight, in order to smoothen it to perfection. And that's how it really works.

In my country, a headlight restoration kit costs about 40 euros, while I bought the car coffee mug heater for only 8 euros!

After a quick search, some examples I've found of the kit and the mug itself on amazon:

https://www.amazon.com/GEZICHTA-Atomizing-Headlight-Restoration-Restore/dp/B08NW2X6R2?th=1

https://www.amazon.com/Brentwood-Electric-Coffee-Stainless-Steel/dp/B009WXAYH0/ref=sr_1_7?crid=3GA3K9BE3J9AP&keywords=car%2Bcup%2Bwarmer&qid=1706398373&sprefix=car%2Bcup%2Bwarme%2Caps%2C189&sr=8-7&th=1

I'm pretty sure you can find a better price for the mug with a little more research.

• Instructions:

Buy a 12V car coffee mug heater, some cheap acetone and print the funnel in PLA. Remove the “o-ring” from the mug's cup and place it on the funnel. Plug in and use.

Just a side note. Presumably, PLA does NOT get affected by acetone. To all my tests, I found out that it DOES. PLA too, starts to soften and melt by acetone, but in a more slow and controllable manner. So, do expect some melting of the inside of the funnel, but you still have a lot of time to accomplish your task. In the worst case scenario, you can always print another funnel ;)

• Q&A:

- Hey man, this thing looks ugly.
- Yes, it does.

- Hey man, couldn't you design it any better?
- Yes I could, if only I knew how! To make matters worse, consider that the initial design was made by my friend Michael (thanx man) and then "improved" by me… I'm really an amateur in 3D design and try to design functional parts, not pretty ones. Hope I can get there some time in the future though.

- But really, does this ugly think actually work?
- Hell yeah it works! Unfortunately, I still haven't found the time to treat my car's headlights, but I've done some tests to some printed ABS parts I have lying around, and it definitely was able to melt evenly the top layer and make it smooth and shinny. The theory is there and it's simple, no magic involved. Just have patience and wait about 15 minutes for the acetone to start evaporating.

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I will be posting photos of the headlights' before and after in the following weeks.

Enjoy!