So how would you guys build this custom control?

Thanks I will give it a try, and post the full example once completed for others.

Im building a Ticker User Control and my dependency property's that directly bind to the XAML which works great, but I have some dependency property's that drive the Beating Internal Class which controls the motion of the three bars. When I change these in the viewmodel they have no affect on the Internal Class Property's so I cant change the speed or starting length and so on. I though if I passed in the Code behind class into the Beating internal class I could do it this way, but i almost need an onPropertychanged event to force the update. thanks Madaxe XAML User Control

Spot on, sometimes its the wood for the trees. thanks a bunch Madaxe

Within my View Model i have a property and backer to bind to the ControlHideShow, I don't get a bind error but if I change the default value in the View Model nothing happens.  If I don't bind in the Implementation XAML and set Visible or Hidden it works so why can I not bind to the ViewModel thanks Madaxe

Public interface ViewModel
{
        Visibility ControlHideShow { get; set; }
}
    
public class MainPageViewModel : ViewModelBase, IMainPageViewModel
{
    
        private Visibility _controlHideShow = Visibility.Visible;
        public Visibility ControlHideShow
        {
            get => _controlHideShow;
            set{ _controlHideShow = value;  OnPropertyChanged(nameof(ControlHideShow)); }
        }
}

Implementation XML

ControlHideShow="{Binding ControlHideShow}"/>

Custom Control XAML