Imports System.Drawing
Imports System.Drawing.Drawing2D

Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Dim ellipseRadius As New Drawing2D.GraphicsPath
        ellipseRadius.StartFigure()
        ellipseRadius.AddArc(New Rectangle(0, 0, 20, 20), 180, 90)
        ellipseRadius.AddLine(20, 0, btnClickMe.Width - 20, 0)
        ellipseRadius.AddArc(New Rectangle(btnClickMe.Width - 20, 0, 20, 20), -90, 90)
        ellipseRadius.AddLine(btnClickMe.Width, 20, btnClickMe.Width, btnClickMe.Height - 20)
        ellipseRadius.AddArc(New Rectangle(btnClickMe.Width - 20, btnClickMe.Height - 20, 20, 20), 0, 90)
        ellipseRadius.AddLine(btnClickMe.Width - 20, btnClickMe.Height, 20, btnClickMe.Height)
        ellipseRadius.AddArc(New Rectangle(0, btnClickMe.Height - 20, 20, 20), 90, 90)
        ellipseRadius.CloseFigure()
        btnClickMe.Region = New Region(ellipseRadius)

        ''Ok success, if you want to change ellipse Radius, you can change all properties(20)
        ''As you can see like this.
        'Yeah successfull,
        'Thanks for watching, if you want to download this, link on description
        ':)
    End Sub
End Class