Thanks to the creators of the models:
https://www.thingiverse.com/thing:3273007

https://www.printables.com/en/model/911930-reinforced-rear-fender-replacement-for-xiaomi-m365/files

https://www.thingiverse.com/thing:3835209

Im a beginner in modeling and it took me quite some time to achieve this. I took the reinforced fender as base model, since it has no clip and i already threw away my original one i needed a new one. So i cut off the one from espaciodrone's rear fender and placed it in the right place. Then i placed the skull at the rear light place. The  part where i almost snapped was when i had to delete the connections in the middle of the skull to only have the front part of it. My last two steps for the rear light were to poke holes in the eyes to the backside of it for the wires of the LEDs and to create the lids for the eyes.

I created this rear fender because my original one broke.

The original LED's are 5V.So i ordered the 3mm ones from ali:

https://de.aliexpress.com/item/1005005382862393.html?spm=a2g0o.order_list.order_list_main.5.68325c5fnFHBlr&gatewayAdapt=glo2deu

The soldering was a little bit tricky. I insulated the wire from the led with shrinking tube and put them through the holes. then i soldered each wire with the matching color (reds with reds, blacks with blacks) together. another shrinking tube over each soldering point and a bigger one over everything. I hope mine is sealed :P

I think the 5mm will also fit and give a little bit bigger base light.

I kind of f'ed it up with the acrylic glue on the eye covers, but still looks pretty dope