It's a mixed media plaque, which combines collage and marbling.
The door frame is made up with an old map (dating back to the 30s I think), while the area inside the door frame is covered with marbled paper squares.
Marbling is often referred to as "painting on water", therefore this technique is perfect for conveying the idea of liquidity, moreover I find it extremely fascinating (see previous post).
Why a door? Because the surface of water, on which the paint floats, represents a kind of passage to a mysterious underwater world, where all the hues of blue, green and yellow blend together and whirl like in a magic kaleidoscope.
That's why the inside of the door is covered with little colored squares, in order to reproduce the color-changing, light-reflecting ability of water.
That's more or less the feeling I wanted to convey.
Combining different techniques and materials is new to me, I usually chose one medium and stick with it, but experimenting new ideas is very liberating, although I'm not really sure about the results.
Here are some details: