For the chair, if you have it in OBJ format you could re-texture it in any 3D application.

For the wall, build your wall as 2 separate levels (if your wall is 3 m. high, build level 1 at 1 m. and level 2 at 2 m. and no floor in between), give level 1 a color and level 2 a striped texture ;o)