I have several rustic workshops coming up this summer and I've started thinking about old and new ways of introducing "rustic".
A third way is to copy a traditional form using rustic materials. This child's high chair has very nice proportions which will look even better in branches or driftwood. By copying, the rustic does not have to also become an engineer or designer. S/he can keep the energy focussed on the subltety of the construction: the diameters of the wood, the textures of the bark, the placement of beauty marks on the branches.
A sixth way is to change scale. Try something LARGE or small. Things are revealed in the struggles and delights of scale.
A fourth way is to start with a simple constructed form: a frame, a desk... anmd add natural materials over and onto it.