Today, I designed a parametric model of a bed. All the components (foots, base, rest and support) of this bed depend on only 1 parameter. It is the radius of the foot-base.
After opening the file, expand the ‘ArrayFoot’ and select the ‘FootBaseSketch’ in the tree view. In its data properties, you can change the radius of the foot in the constraints section.
Certain expressions are used to set the dependent constraints. Refer this link for further readings: (https://www.freecadweb.org/wiki/Expressions)
The FreeCAD file of this model can be downloaded from this link: ParametricBed
Feel free to test and review this parametric model.