Disconnect trapdoor shape from material

A lot of times when building and you use things for their look, not their function, you often want it to represent something else. For instance how you can use the solid variations of trapdoors for shelves, or some of the other shapes are suitable for cages or grates. Or wrap them around light-sources or fluids for specific industrial looks.

Now, with the way the material is connected to the shape, you cannot have acacia shelves, because from what it looks like, the stuff would fall through the holes.

Maybe sometimes what you'd really want would be the i "shape" of a spruce trapdoor (which is solid nailed planks)  but with the planks made of acacia, since spruce doesnt fit your scheme.

As for how to get the specic shape you want,from the material you want to use, the most simple version would be to allow you to change to next shape by putting the trapdoor in the crafting area.

A slightly more complicated solution would be the default shape(what we have now?) being craftable, and all the other shapes being available trough either a new workbench of some sort, or trough the stone-cutter. 

PS. Obiviously this would mean about alot(80?) of new textures, so it is not trivial. But, it would allow you to take a step back and define a set of shapes you want. And then, implement the material/color for them. Thus, when adding a new trapdoor in the future, the shapes are already set. Or, if you really want to add an addtional shape, this can be done without adding an additional material. DS.