Q:

Creating polygons with different heights in Qgis2threejs

i'm trying to display a polygon in qgis-2threejs which works fine. Now i want to adjust the height on the sides of the polygon, so that i can vary the body of the polygon. 
Basically i want to display different fractures inside of a mountain with the height of each polygon adjusted to the surface. 
See here: 

A:

As far as I know, it is not possible to get a sloped polygon in Qgis2treeJS. 
However, you can create a second DEM with your mountain and display your lines on that surface. 
You can then use your lines layer in Qgis2threeJS and select "profile" as object type. Then use the parameters Zcoordinate (mode absolute value, I'd recommend 0 ) and Height (the altitude of your layer) to draw a surface all the way through your model. 

