Parametric handle

You can adjust the mounting holes distance setting the "interaxes" parameter that suits your needs. The handle size will change accordingly. Then tweaks the "handle_size" parameter to adjust proportions. The other parameters control the mounting holes dimensions.
Be sure to tweaks parameter with a low "quality" value (32) then raise ( 128 ) for final rendering.

STL provided is for a small handle 58 mm between mounting holes.