Really Bare Bones Board - Arduino compatible.
Just got 5 of these recently on a combined order with TXD & LOL. very small, complete kit and (perhaps overly) thorough build instructions on the website.
I think these are a great option for introducing uControllers to newbies. Designed to plug into a bread board, the 0.1”pitch means it wouldn’t take any effort to include in a custom veroboard project. Better than classic Arduinos for long term solutions.