Actually writing your own Toolbars and Menus is beyond the scope of this little series. If you are interested in learning how to do that, I would recommend that you download several of them and open them in your favorite text editor. Then go to the my.opera.com Customizing Opera Forum and hang out with the super cool folks over there who create these customizations for themselves and others.
Please note that it may take a little while before new setup come out for Opera8. However, you can start making your own customizations to the keyboard layout right away.
By the way, for more about the toolbars themselves see Day 21: Toolbars.