A tool for cutting grass and vacuuming the clippings at the same time.
As shown on the header image, the trimmer part has a skirt all around it. That prevents the grass clippings from flying out on the side. A strong vacuum pulls all the clippings into the collection bag. Imagine an oversized stick blender that also vacuums everything it minces.
The suction tube can be made out of aluminium so that it's lightweight but strong enough to support the trimmer head.
When you have to trim some sensitive areas where you can't have the grass clippings flying all over the place. For example around swimming pools, indoor artistic patches of grass, etc.
I found this concept that sort of goes for the same idea, but I propose a more useful implementation that does not require crawling to use. This is suitable for serious work.