40mm Fan Duct for Anycubic Kossel with Trigorilla for TMC2130 stepper drivers

I originally used Facocero's fan duct, the 'Dig Dissipator' edition.
At first I thought it worked OK, but later found that it seemed insufficient. The drivers still overheated and shutdown.

I felt a key issue with Facocero's design was that the fan could move air around below the pcb, and that would be an easier path, and waste a lot of the air movement the fan creates, instead of sending it through the duct.

Additionally, as I have TMC2130 drivers I needed to use the SPI pins, and s