How do I scale only one side? The switch is too small, but if I try to scale it, it will end up with a side clipping through the outer box, which is something I do not want at all.

If anyone can help me here, I would really appreciate if.
you can scale with restriction on the axis.
press S and then an axis on keyboard(x,y or z) to scale only on that axis.
and press S and then shift + axis to restrict the scaling on that axis.