Generating Random RGB Colors
You need to change/add just one little thing. You need to call the Randomize () method before using the Rnd () method. You should only call it once, so it would be good, to call the Randomize() method inside of the constructor of your class like:

Private Sub Class_Initialize()
    Randomize
End Sub


If you don't do this you will get for each iteration the same "random" number.
Don't get me wrong, this doesn't mean that all numbers will be the same but assume you start your application. For example you will get the RGB numbers 11, 54, 142 for the first call of your method. If you restart your application you will again get these same numbers on the first call.

To prevent this, you need to 'seed' the Rnd () method to get random values each time.