While surfing the internets, I found this list of drummer jokes that someone has maliciously edited into bass player jokes. These are the worst ones. This is not funny at all. This is the sort of thing that gives guitarists a bad name.
Q: How many bass players does it take to change a light bulb? A: Only one - but the guitarist has to show him first.
The easiest way to make a pickguard is to go to eBay and buy one, ready-made. However, if that doesn't suit your project, you can also find a wide assortment of blank materials to make your own design from. Work out your design full-sized on paper first.