As part of a larger project, small things emerge; this is a copy of a clip that is used to hold an item in place when mounted inside a tube/hollow section of a part (the tube needs a suitable groove).
Open the *.fcstd file using FreeCAD (www.freecad.org).
Make sure to see the "Combo View" (right click in the toolbar area for pop-up menu to select it from)
In the Model tab of the Combo View, expand the C-ring_inner, Body and
change the thickness by adjusting the Pad... Length parameter
change other parameters by adjusting Property tab content after selecting the SideSketch...
Hit TAB-key or ENTER after changes to see them applied.
Expect to see strange things for extreme values or LARGE CHANGES (the last is a limitation of the FreeCAD solver as it seems to me).
Not tried to print this yet - part of larger project.