This is still very much a work in progress. I am attempting to build this switch (site in German):
It is an 8 port automatic TOSLINK switch. The creator (micro) requested that if anyone else build it, they not do it for profit, so I will do my best to respect his wishes.
All told, they parts cost ~$40 a board, with the price mostly dependent on the cost and availability of the TOSLINK ports. I am making 3 boards to start, and can make more or sell kits if there is enough interest.
If you are interested, check out this sale/interest thread:
https://shmups.system11.org/viewtopic.php?f=4&t=62408
Progress 5/20/18
The boards arrived about a week ago:

I did a test fit to make sure everything was the right size. The only thing wrong is the tact switch. It is the correct size, but too tall; this will work but I will order correctly sized ones soon to put on the final board/kit.

I tried programming the board without success, so decided to finish assembling the board:


After actually checking the ISP pinout instead of assuming ground was pin 1, I realized I had the 6 pin connector on backwards. I’ll try to program it tonight with it on the right way.
Update!!
Plugged in the ISP cable correctly this time and it worked! Here is the LED test mode:
And even though I say “7 LEDs” in the video, there are clearly 8 working!