My dad has a Poulan Pro trimmer with a handle attachment that they don't make anymore so I designed this clamp to attach the handle to the trimmer itself. The 2 pipes I modeled for were 26mm and 20mm diameter.

What I used to attach it.

4x M6x1.0 Phillips screws 60mm length

4x M6x1.0 coupling nuts 16mm length (shorter will work as well)

4x washers (6.4mm inner diameter, 12mm outer diameter)

I printed this on the Bambulab x1 Carbon using their PLA Tough filament. I also wrapped a thin layer of electrical tape around the pipes before attaching the clamp to add friction to keep it from sliding.