Creating family
Start with choosing Metric Generic Model face based from the Metric Templates. On the base by creating some reference lines, we can assign boundaries of our project, it will also help us to create symmetry. We can draw the shape of our family for e.g. wooden panel. Using commend Extend: Rectangle, and put references boundries on our model; by pinning it we can change proporties later with only one move.
To make a pannel in shape we really need,like existing Ikea panel, we have to give it all the real dimensions that panel has. Using commend Measures we can add each value, and if its not correct we can edit it, and put our own. To keep symmetry we can use also commend EQ above the dimension. We can also add the parameter names in Parameter Properties, adding a Name, which is later visible in our project. By that we can later change dimensions in the winow of Properties. Approve the panel with the green tick.
Now we can go to the 3d view and see the model. If we didn't do that before we can change some parameters now, like height. Use commend Materials and add materials to your project library, by that in the properties window you can add to the pannel a material of a wood, which is visible on the screen after choosing a realistic view in the icon below the labour space.
Pannel is ready. If you need you can change values or create another one, with a different dimensions, in that way you can create whole the family of ikea panel with a different dimensions, that they sell in the store.