Salome, preparing model for MRFSimpleFoam

Hi,

I'm trying to prepare a model in Salome 2013.1 for MRFSimpleFoam solver in OF like here:

openfoamwiki.net/index.php/MRFSimpleFoam

Unfortunately I don't know exactly how to build it. I've made the geometries starting from making a box and cylinders, then I cut the space in the outer cylinder for inner cylinder and next I cut the space for box in the inner cylinder. Everything worked fine but the geometries must have shared faces.
I have only managed to make an assembly from outer and inner cylinder but failed to add the box.

Has anybody done something similar? I will be very grateful for any help!

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postimg.org/image/pb0lg7een/