Hey, lets define designing your own.
If we're seriously designing, we would be using our own aerofoil, our own gyometry with regards the wing and stab placement, trust and rudder line angles and a million other things... the knowlege of which only comes from many years of competitive flying.
Why bother doing this?

There are several excellent diagrams, side views and PDF format instruction available over the net of many of the lastest production designs. You can see the aerofoils, the measurement etc etc...copy them! Use your artistic talent for doing subtle changes to the shape, modifying it to you personal taste and building technique. This isn't copying, it's just being smart and doesn't infringe any copyright as long as you don't start commercial production.

This is absolutley the best starting point as there isn't any correct aerofoil shape etc...it's all personal. Take the Synergy for example.
That has a real thick aerofoil that in the hands of a certain Frenchman can perform like magic... yet everybody that I know, hates the aeroplane as is... and have produced there own wings with a far thinner foil at the tip. One, a worlds competitor has even made a new stad, again featuring a thinner section to suite his style.

A fun project thats done by many. Start looking.