Create two separate and movable rectangles inside a picturebox

I really hate promoting my own work, but you might get some ideas from my article Create your Own Runtime Movable Windows Forms Controls[^].

The issue you have is in pictureBox1_Paint, you are only rendering one rectangle, not each rectangle in the list.
You need to change this:

Private Sub pictureBox1_Paint(ByVal sender As Object, ByVal e As PaintEventArgs) _
    Handles PictureBox1.Paint
    e.Graphics.FillRectangle(New SolidBrush(Color.Gray), rectangle)
End Sub

to:

Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) _
    Handles PictureBox1.Paint
    For Each rect As Rectangle In rectangles
        e.Graphics.FillRectangle(New SolidBrush(Color.Gray), rect)
    Next
End Sub

Thank you for for your interest in my project. I've got as far as I can with the code. I've implemented the list and can track whether the rectangle has been clicked or not, using Contains. I've included a message box and some labels to temporarily keep track of what's happening. A rectangle is created on the form loading but I rather want it created on a button. However, Button1 creates a second rectangle on top of the first and disappears when clicked and I can't see how to update the picturebox_paint with different values to create additional rectangles. So far, I can also move the single rectangle around the picturebox. Any further advice would be appreciated.

Public Class Form1

    Private rectangle As Rectangle = New Rectangle(70, 70, 100, 150)
    Dim rectangles As List(Of Rectangle) = New List(Of Rectangle)()
    Private isMouseDown As Boolean = False

    Public Sub New()
        InitializeComponent()
    End Sub

    Private Sub pictureBox1_Paint(ByVal sender As Object, ByVal e As PaintEventArgs) Handles PictureBox1.Paint
        e.Graphics.FillRectangle(New SolidBrush(Color.Gray), rectangle)
    End Sub

    Private Sub pictureBox1_MouseDown(ByVal sender As Object, ByVal e As MouseEventArgs) Handles PictureBox1.MouseDown
        isMouseDown = True
    End Sub

    Private Sub pictureBox1_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs) Handles PictureBox1.MouseMove

        If isMouseDown = True Then

            Label1.Text = e.Location.ToString
            If Contains(e.Location) = True Then
                Label2.Text = True.ToString
            Else
                Label2.Text = False.ToString
            End If

            rectangle.Location = e.Location

            If rectangle.Right > PictureBox1.Width Then
                rectangle.X = PictureBox1.Width - rectangle.Width
            End If

            If rectangle.Top < 0 Then
                rectangle.Y = 0
            End If

            If rectangle.Left < 0 Then
                rectangle.X = 0
            End If

            If rectangle.Bottom > PictureBox1.Height Then
                rectangle.Y = PictureBox1.Height - rectangle.Height
            End If

            Refresh()
        End If

    End Sub

    Private Sub pictureBox1_MouseUp(ByVal sender As Object, ByVal e As MouseEventArgs) Handles PictureBox1.MouseUp
        isMouseDown = False
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

        PictureBox1.CreateGraphics.FillRectangle(New SolidBrush(Color.Brown), rectangle)

        rectangles.Add(rectangle)

        MsgBox(rectangles.Count.ToString)
        Dim sResult As String = ""
        For i = 0 To rectangles.Count - 1
            sResult = rectangles.Item(i).ToString
            MsgBox("Rectangle " & i.ToString & "  " & sResult)
        Next

    End Sub

    Public Overloads Function Contains(ByVal pt As System.Drawing.Point) As Boolean

        If rectangle.Contains(pt) Then
            Return True
        Else
            Return False
        End If
        Return False

    End Function

End Class