How to include the curvature when build the layer

Hi everyone
I want to build a solid-water-solid system with Materials Studio 6.0 and the desired model is shown shematically in Fig.1 with the fluid full of the slot.I have read the tutorial of layer buid, however what I done is Fig.2 and the planes at bottom and top are plane. How can I creat the curvature substrate at top as Fig.1?
Fan Li
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                Fig.1

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                Fig.2