Before all those 3D model implementations, I would be glad just to see the block system changed:
- Be able to build a Block on top of a Half block, or combine two half blocks and still be able to put a full block on top of that;
- Be able to build round structures (well, round towers, etc.)
- Be able to combine two ramp blocks together (it's still a pain to build roofs)
- Be able to place a half block verticaly.
This simple 4 things could save a lot of disapointing builted strucutres.
Those roofing materials are great ideias too
try building with timber and not blocks most of what you asked can be done with beams and planks