By combining multiple parts from the MakerGrid system with each other it becomes really useful. This model offers one sided and two sided rails that are 10x10mm thick. They don't offer the stability of the bigger 20x20mm build cubes, but they are very handy if you need them to connect stuff.
I recommend to print these and other build cubes if you have some left over filament.
The author hasn't provided the model origin yet.