Modular system

Hello everybody

I am trying to develop a modular reconfiguration parametric system. I have a problem with  getting the geometry out of the grid. I have got some results but then I stuck. I need to get this kind of module as on the picture. The main demand is to keep all the edge sections constant in sizes (the edge sections are the same). 
The idea is about a possibility to deform the grid leaving the modules with the possibility to fit each other.

Could someone please give an advice how to make it work? Here is the scheme itself.