This is nothing interesting, just a small attempt at making "smooth" topography with QGIS, If you download a height map from STRM or GMTED and apply a colour to it the result is "too accurate", it's rugged and doesn't always look good, especialy if you want to make a less professional looking map.
So instead i exported several raster pictures with QGIS each with a black and white picture for each elevation level (0-100m, 100-200m...) then inserted them in inkscape and put them on top of each other, then i used the vectorize a raster option to vectorize them (note that directly vectorizing a coloured heightmap often gives bad results), i did this for each level then applied the "smoothing" effect to each vector shape, thenapplied a colour.
This took 5 min of downloading from STRM and 20 min of fiddling around, it shouldn't take too much more time for a larger map, STRM data can take a long time to donload but 75m GMTED data are nearly as accurate and much quicker to download, so i'm sure one could make a similar map on the scale of a continent in less than half an hour.