One you have draw the template on to the hardboard cut it out. You should use a small hand saw or even a hack saw.
Follow the lines carefully, and take it slow.... I sound like a surf dood...eh?
Next plain and sand down the edges until they are nice and smooth Tip: You will be making two of these, but on one of the keep the smooth side of the hard board smooth eg. dont sand it.
You finished result should look like picture 1