Random Scaled Polygon - Different Coordinates And Colors

On click, I'd like this piece of code to create new polygon, shown in multiples with different coordinates and colors, sizes and orientation. Color and polygon in multiples works. My issue is I'd like to add more code that will allow each of the multiple polygon created scaled randomly and rotated. How to keep the polygons inside the canvas?

So far looks like this when user clicks start: [URL]

Code:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles startButton.Click
Dim endCount As Integer = random.Next(1, 10)
Dim plotPoint As New Point
For count = 1 To endCount
[Code] .....