I imagine it would be easy to damage your drill irreparably if you over-strain it. So if you make one of these, don’t make the disc too big. The outer edge would move faster but would put lots more torque on the drill. My drill was fine with this 7”(?) light disc and only needed one battery-change for the job – but don’t blame me if yours starts smoking. : – (
It probably won’t work on grass. Grass is just so much tougher than these weeds (redshank mostly) and needs a faster/sharper edge to cut it. That’s why real strimmers and lawn-mowers have bigger circumferences and spin faster.
As with all hand tools, the shape and position of the handles is really important. This contraption is very maneouverable but you need to be in complete control all the time. I found these bicycle handlebars worked really well