helix-toolkit/helix-toolkit

At the moment I switched to toolkit.wpf there is ItemSource:
so I can add objects at runtime and access them later. But with DX I have no idea how to do that:
If you can show me the alleged example where I can add a box at runtime and then move that box in the codebehind at any time I would donate you a case of beer!

View:
<h:HelixViewport3D ItemsSource="{Binding Wpf3Objects}" Height="300" Background="{h:LinearGradientBrush Gray, White}"></h:HelixViewport3D>

ViewModel
private ObservableCollection<Geometry3D> _geometryOc;
public ObservableCollection<Geometry3D> GeometryOc.
{
get { return _geometryOc ?? (_geometryOc = new ObservableCollection<Geometry3D>()); }
set
{
SetProperty(ref _geometryOc, value);
}
}

var myTransform = new Transform3DGroup();
TranslateTransform3D myTranslate = new TranslateTransform3D(loads.PosY, loads.PosX, loads.PosZ);
myTransform.Children.Add(myTranslate);
BoxVisual3D boxi = new BoxVisual3D();
boxi.Height = thickness;
boxi.Length = lenght;
boxi.Width = width;
boxi.Transform = myTransform;
Wpf3Objects.Add(boxi);

Translate
TranslateTransform3D myTranslate = new TranslateTransform3D(x, y, z);
Wpf3Objects[ooo + 1].Transform = myTranslate;

Translated with www.DeepL.com/Translator (free version)