I have to admit I'm a bit underwhelmed - it feels too obvious now and the skull itsell is still blurry. After a bit of brain storming on mastodon, I'm now at the following stack up:

4 Layer boards, but thinner than 1.6mm. The skull details can be on bottom layer or the one after the FR-4. I will probably remove the reflection from the board, moast of the time it looks like a hello kitty bow and isn't brighter than anything around it. Just realised that I don't like the highlights on the diamond scarf brooches. Wondering about adding green LEDs behind them.

The light bleeding is gone thanks to the 4L with two layers basically being just copper. 

Programming the CH32V003

The hackaday badge can be used as a programmer for the CH32V003, it even came with a little board that featured some LEDs and the chip. After some group-effort debugging we fixed the python script in the discord and were able to let the LEDs blink differently.

So from V1 to V2 I changed the chip to feature the CH32, forcing me to try compiling code for the chip next. Thankfully there's ch32v003fun by CNLohr! I followed the instructions and installed the RISC-V toolchain threw brew first. I skipped all the probably helpful programmer tips and guides, since I already had my trusty badge.

The "fun" examples for the chip included code for neopixels, but the chosen pin was not available on the 8 Pin version. 

#define NR_LEDS 160
const int pin_number = 6;
#define BITS_PER_LED 24
#define TIME_SLICES_PER_BIT 4 // 4 is more reliable, 3 has less overhead.
const int gpio_pin = PD6;
GPIO_TypeDef * const gpio_port = GPIOD;

Further down in the example there's a hidden PD0 that I replaced with "gpio_pin" later - I should turn that into a pull request [edit: done]. For whatever reason I don't know yet: when I change the LED number to 4, it gets very flickery, probably some timing that scales with the number that doesn't like a reduction to 2.5% 

I also don't quite understand why there's a pin_number and a gpio_pin variable.

Production of 3rd version of the board will start on February 5th - thanks to purple stopmask, ENIG plating and 0.8mm thickness. I've ordered 50 and will populate as many as I have chips and LEDs for it for Hackaday Europe!