This is a selection of parts that I have made to attach whiteboards to walls, especially around corners. I am calling it a work in progress even though I probably won't do anymore to it as it isn't really complete for a "general case" but there is enough to do the job that I needed it to do.

The light switch spacer is included to allow outlets and light switches to be installed in a wall box at normal depth that is located in the middle of a whiteboard. For switches I recommend gluing the spacer to the back of the switch cover plate with the switch installed at normal depth to the wall. This will recess the switch by the thickness of the whiteboard. There is still plenty sticking out to be able to flip it, but it is less in the way while writing on the whiteboard. For outlets and decora switches, put the spacer between the outlet/switch and the wall box and then install the cover plate without any extra spacers between it and the outlet/switch.