To fix something like this: select the edges on each side, edit mesh, then press bridge to fix it. Using the fill hole tool in the mesh tab will not work.
Here is the model fixed with the bridge tool:
This happens when you use the fill hole tool:
You can fix this by selecting the vertices and clicking the one on the other side using the multi-cut tool. This would leave you with a gradient like this:
You can fix this by holding shift and right-click to open a different menu, go to soften/harden edges, then go to set borders.
I made this by making a cube, extruding it, going to mirror in the mesh tab, reflecting it on the x-axis, and rotating it 90 degrees.
I made a hole in the shapes and then separated them, moved one shape further away and moved it up, combined the shapes, selected the edges on the holes, bridged them to make this:
I then did the same thing to make a frame like this:
Added more of these frames to create some architecture:
I modelled a chair in Maya:
Finished render of chairs in an environment:
