As of this week, the PCBs have been manufactured, and assembly is underway.
The next step after assembly is testing to make sure the components were placed and soldered correctly. My manufacturer in China and I have identical test fixtures that make contact with the connectors on the shield and do a simple test to make sure the circuit is functioning correctly.
I designed this test fixture for the SmartLED Shield for Teensy 3, but because the SmartLED Shield for Teensy 4 is the same size, I’m able to reuse the fixture with only minor changes to the test firmware.
The final design files are up on GitHub if anyone wants to take a look. The hardware revision is "V5", building off of the SmartLED Shield for Teensy 3’s revisions which got up to "V4".