Interesting idea. As one with back problems, the Husqvarna DJX129 is a major pain to run for any length of time. End up stopping every 5-10 minutes and stretch my back. That's why I went to a wheeled string trimmer where all the weight is on the two wheels
Got one last season. Some shortcuts in their design...mine's 3.0 I think, the clamp bolts that hold the arm to the shaft ( mine's a Ryobi ) could easily strip.
That being said I love it.
Attempting to correct for my being 6'2" with back problems and this really helps.
A welder or such could probably create one but why not support a US business?
As this is my first venture into battery powered trimmers and away from corded---last corded was B&D with power but some problem...B&D sent me one on principal and I sold them both to finance the Ryobi... I figured why not try this arm also.
My challenge now is what used to take 45 minutes with the corded now takes 20 minutes and I actually enjoy trimming....