Bushing with flange, parametric, FreeCAD

The STL file is an example; drill an 8mm hole, and push in this thing, then use a wood-type screw to fasten anything to it, using the center hole.

Change parameters in the Property tab of the Combo-view of FreeCAD. The only "parameter" that contains a calculation is the Flange (Cylinder001_...) outer radius, change the "3" to any number you like, that FreeCAD can accept.