I would look for pictures of the one you are interested in. The manufacturers' websites are a good place to look. Some of them may even have some basic 2D drawings. Then, just explore what sketches and features you need to model it. Hope this helps.
I cannot model it for you as I am doing a repair install of my software at the moment, but I have some suggestions. Video-Tutorials.Net is a good online tutorial for CAD software. if you want to know how to create a model of simple water tap, you can contact this Email id: email@example.com.
web site: www.video-tutorials.net/vtnet/
I have one video on ToolBox Videos - Ball bearings tool of this company , you can see here: http://www.youtube.com/watch?v=JJzoqP3ZuV8.
Hope this information helpful for you! Have a great day!