A simple handle with 4 3mm holes for screws.

Width is ~150mm

It holds 4kg with ease when printed with 15% infill (I haven't tested anything else).
It's a bit challenging to print because of a load of supports in any orientation.
The center supports also weren't too easy to remove, at least in my case. Some filing had to be done.
After a few failures it seems to print best with the mounting plates attached to the print bed.

Happy Printing!