Geometric designs can be used to pick up on colours in a room.

For example the curtains and the coloured glass in this kitchen

This "trompe L'oeil" panelled effect was created with 1930s wallpaper patterns as inspiration. This works well where structure is needed in a characterless room.

Squares in this stylish dining room are painted in Dead Flat, Matt and mid sheen giving and interesting finish.

In the same house as above the chimney breast is picked out in much smaller squares, the design I think is pleasingly sharp and elegant