I’m currently working on a more complex project that uses double sided assembly (and a weird USB-C connector). To practice these things a little, I ordered some low cost boards to get used to that connector and explore double sided reflow (which seems easier than I expected).

For those who are interested, this is a reference design from framework computer for their expansion card system. It can be programmed with circuitpython or Arduino and utilises a SAMD21 microcontroller.