My neighbour had a stroke a while back which made him unable to carry his 20kg battery charger/jump starter around so I designed some clamps and a handle to make it easier for him to roll the charger around instead.
I made the parts to fit a tube with an external diameter of 25mm but I have uploaded Fusion 360 files so you can adjust the sketches to fit your need.
For mounting the clamps to the charger I used some M6 allen screws.
The wing screws are M8 with corresponding M8 nuts.
There is also a M6 allen screw and nut that secures the handle to the tube.
I printed these parts with 4 perimeters and 50% infill in PETG.
Depending on how well your printer and settings can manage overhangs you might need to print with supports.
The author hasn't provided the model origin yet.