...or for the old fashioned folks among us you can just use balsa....

But Dick is right. Simple gliders like this are a great way to play with aerodynmics. A flat airfoil acts the same as a thicker symetrical airfoil. You can also simulate cambered airfoils by just curving in some camber into the wing and stab so now the wing and stab are lifting. A long stick for a fuselage with sliding wing and tail will let you play with tail moment arms to see how lengthening the tail increases the tail volume coefficient and allows an even further rear CG but still retains positive pitch stability. Make the taill long enough and you can actually balance the model at or behind the trailing edge but still have positive pitch stability.