A few things might inhibit an Arduino, AVR, or PIC user from making ... So if you have a breadboard and a USB to serial adapter, you could build the bare bones version of this for about $6 and ...

[Hans Peter] wanted to move away from using full Arduino boards in ... in order to test it on a breadboard. The first board he assembled was too loose in the USB port, but he added some tape ...

It also has fewer pins than other boards, and its USB port is somewhat outdated ... make it perfect for prototyping with a breadboard. However, Arduino also offers this board without headers ...