This model is a combination of the 3 Valles Marineris meshes provided by NASA here: http://nasa3d.arc.nasa.gov/detail/valles-marineris-6x
The models were originally created by Northeast Planetary Data Center, NASA RPIF System, Seth S Horowitz & Peter H. Schultz.
I have combined the 3 meshes into one continuous model, and optimized it to reduce the polygon count while retaining the important details.
This print was scaled to 18cm, and printed in PLA. It was then painted with acrylics and inks.
It looks good mounted on this wide display stand: http://www.thingiverse.com/thing:1363286
25% infill and 6 top and bottom layers were used to ensure a smooth surface on the flat areas.
As this was printed in blue PLA it took a few undercoats of white to cover up the blue tint. I then gave it two coats of yellow ochre acrylic, multiple brown, red and blue washes, and then dry-brushed with lighter tones. Finally I highlighted the ridges and craters with a 0 brush.