Don't know if someone said it before... a friend of mine pointed me to KiCAD 3D components which can be copied into DipTrace folder. Some of the 3D objects can be used directly, and others after some adjustments, as scaling, translating (operations made inside DipTrace when you assign a 3D object to a component), etc...
Some of the KiCAD objects are prettier than those on DipTrace.
Maybe the guys from DipTrace can rework some components starting from KiCAD ones...
Here is a 3D board with3D objects borrowed from KiCAD (that board contains also some footprints imported from Eagle).