I finally found some time to finish this one. It is a still life of my grandmother's mandolin-banjo, and a souvenir of our trip to Venice in a corner of my parents' living room.
Quick sketch in Artrage, back then on the Windows platform.
Colouring and adding detail to the mask in MyPaint. Moved to Ubuntu in the meanwhile. Basic colors were laid down, and lots of details were added to the mask at this stage (e.g. the sheet music fragments at the cheeks and forehead).
More shading was added to darken the background and make the candle a more pronounced lightsource.
Decorations are added with special MyPaint brushes. Some garlands were added as a hint to Venetian carnival, and the mask's ribbon was drawn.
Final brightness, contrast and color adjustments in GIMP. I went for an old look with these quite drastic final adjustments. The overall tone was adapted, but a bit of the original color contrasts were kept. Some noise was added to the shadows and midtones too for an 'aged' effect.