Sorry, I could not make it through!

Aside: Although not strictly custom silicon, one can get close to making a custom chip with a Programmable System On Chip (PSoC) made by Cypress who look to have been "consumed". [1]

I did toy with the idea of making application specific "chips" from this system, but couldn't find enough inspiration. The design tooling - last time I looked - was pretty good.

[1] https://www.infineon.com/cms/en/product/microcontroller/32-b...