the mini::out is, as is reflected in its name, a fairly simple breakout board. it enables you to make use of the mini::base in a rough breadboard-and-cables style of way - something which you are accustomed to if you’ve worked with development boards before, and something that will always need to be available for the first steps in any project.
the mini::out has the same basic dimensions as the mini::base and all other mini series extension boards. the bolt holes are made for M3 bolts. and there is another feature on the mini series: the Würth board-to-board connectors are stable enough for any combination of mini::base plus extension board to be fixed in a housing by simply sandwiching the boards package between two housing halves.
size is not the most important aspect for a development-style board. nonetheless we aimed to keep it compact yet robust, again with the goal of making the board::project line viable for more than just desk environments. as a visual aid and to ease integration, we decided to use the credit card form factor as a reference, and the mini stack is exactly half a credit card in footprint at 54.0mm x 42.5mm.