Farben, was considered as a lethal agent but found to be impractical.
But making it is complicated and, in many cases, so costly as to be impractical.
Maybe this sort of system would turn out to be impractical.
If electronic delivery is likely to be impractical, you should mention this to your commissioning editor.
Diaghilev invested some of his profits in costumes that turned out to be impractical.
This potentially valuable line of research is either impossible or so forbiddingly difficult as to be impractical using surplus embryos from fertility clinics.
The busing has proved to be impractical, and so the wing will be constructed after all, though now at greater expense.
Transforming the barn into a studio turned out to be impractical, but she found space at a nearby retreat center to hold weekend workshops.
Bicycles were promoted at indoor riding academies, often rinks from an earlier roller-skating craze, but enthusiasm quickly flagged when long-distance travel was found to be impractical.
Oklahoma law allows use of a firing squad if lethal injection and electrocution are ever ruled unconstitutional, and Idaho can use a firing squad when lethal injection is found to be "impractical," a circumstance that has yet to present itself.
When Wilder landed at WSHU her bosses said they were familiar with her work at NPR and believed she would be able to pull off a feat many thought to be impractical.
