I love the Nucleo, Discovery, and Blue Pill boards, but I find most of them lacking as a reference design. The Nucleo boards have a built-in debugger, which is fantastic, but I found it difficult to go from ST's documented schematic to my own design. They seem to be mostly a kitchen sink type of development board (add all the features!) where discerning only the necessary parts took a lot of time and cross-referencing other manuals. 

The Blue Pill does not have built-in USB support (it looks to be bit-banged from the STM32F103), and one of my goals is to provide a bootloader via VCP or uf2. While some of the Nucleo boards have built-in USB, most are just broken out to pins, as the USB connector is reserved for the ST-LINK chip.

As a result, I've put together my own breakout board for one of the newer STM32 parts based on the ARM Cortex-M0 processor: the STM32F070. I had v01 manufactured by OSH Park, and everything seems to be working (so far). I have a few minor fixes to the layout, and I'm hoping to get the PCB manufactured with white solder mask next time.

While I was able to put one together via hand soldering, it's not something I want to do again in the future. As a result, this project is also giving me an excuse to invest in a reflow toaster oven for "research purposes."