How to extract data from object graphic

Question

Hi everyone,

Am still new with C#, please bear with me as I definitely a noob in this language. I need help regarding on WPF viewport3d and how to extract data/properties/children(seriously i dont know much) from the data  I draw using clasess (mesh, geometrymodel3d, geometry3dgroup, modelvisual3d) which contain in cubicBuilder class.

//###############################################

ModelVisual3D _cubic = new ModelVisual3D();

double Lx = 4; //length of cubic.

double Ly = 3; //depth of cubic.

double Lz = 2; //width of cubic.

_cubic = cubicBuilder(Lx,Ly,Lz)

this.mainViewport.Children.Add(_cubic);

//################################################

as you can see from the pic, I have already drawn the solid. My qquestion would be, how I can get the double value (Lx, Ly, & Lz) of _cubic, from mainViewport after any execution(button click)?  :help: