Altium designer (without vault) only comes with through hole components (resistor, capacitor) in the component library. I want to design SMD capacitors and resistors on my own but I want to reuse the schematic symbol of the default Altium components. How can I do that?
You need to create an Altium PCB library that contains all of your SMD footprints. Once you have your PCB library created, open the SCH library containing the symbols you want to reuse, select the part whose symbol you want, and open its properties (double-click it in the SCH Lib tab, or right-click it and choose "properties"). Then in the "Models" section at the bottom right of the properties window that pops up, use the "Add" button to add your footprints.