Simple rectangular parametric air terminals would be great.
All you would have to do is change the X and Y dimensions of the air
terminal.
The problem with air terminals is there are so many different sizes.
Typically, a rectangular grille is shown as a box with (1) line for return /
exhaust, and (2) lines for supply. It would be nice to have a parametric
function that would allow the user to enter a size similar to how you enter
a size for ductwork. Otherwise a new part must be created for each size if
you want to have the halo'ing and connection functions work. At this point
we are just using non intelligent rectangles. Someone at Autodesk who
actually understands parametric parts would be a hero to the ABS world if
they made this work!