[Feature]: Custom Double Slabs or Compound Double Slope Slab

[OromisElf]

Describe the feature

In my pursuit of perfect aesthetics I needed quite a few shapes not supported by this mod. I had kinda hoped to make some of them by stacking various framed slabs, but from what I gathered that doesn't seem to be possible. So instead, I'd like to ask for this kind of shape:

but instead of it being part of two block spaces, I'd like it in the same block space.

[XFactHD]

This shape makes sense to me, adding it to the list of planned blocks.

Stacking arbitrary slap-like blocks in the same block space is indeed not possible and is not feasible to implement.