Version 1.12.2
I'd like a few shapes/features to be implemented:

• 1/4 block: A rectangular strip that is 1/2 x 1/2 x 1 block.
• Round outer corners in larger radii: Similar to the arch tab.
• Larger plain newels: Make the newels in plain balustrades with newel and plain outer corner balustrade larger, as they are barely distinguishable from the balusters from afar.
• Window frames accept more panes: allow window frames to accept all pane-like blocks, including those from other mods. Examples would include vanilla iron bars, managlass panes from Botania, end steel bars from Ender IO, etc.
• Window frames/panes can be placed in other blocks: Not sure how feasible this is, but the option to be able to put window frames in the same block as e.g. an archway would allow for much more flexible window shapes, like arched windows and diamonds. Could potentially work similar to cladding, where the cladding changes the appearance of the base block but does not occupy a separate block space.
• Shapes that require a "stretched" texture will respect original texture orientation when placed in any direction:
  
  Currently, when a block such as an arch or a slope is placed sideways, the texture on surfaces where the original block texture is stretched/warped will also be sideways. It would be nice if instead these surfaces followed the original texture orientation and stretched the texture in the opposite axis.
  
  This also affects columns; notice how 1/3 up the column two mortars meet, but 2/3 up the column there is a mortar layer missing.
• CTM compatibility: Could be a pipe dream, but CTM for things like slabs, roof blocks, arches/round outer corners, etc would be amazing.

New Blocks: Probably not happening for the foreseeable future. Sorry.
CTM Compatibility: Not planned.
Orientation Bugs: Currently being evaluated / worked on.
Window Frames: I might take this on myself, possibly.