There are times when you need to have an object cut another object.
In this example, the sink is placed on the countertop, but it doesn’t look right in 3D view.
(Now, I know in this case, you might have seen a countertop family with the hole in it that you can adjust. Please read through and see why I think this method is better!)
We can resolve that by editing the sink family and adding a “void” box for the area you want your family to cut the other object. (Lock your void so it flexes with your family, so it changes size when you modify your family size)…
Then in “family Category and Parameters” tab, make sure the “Cut with Voids When Loaded” is checked.
Now, just load the family back into the project, and use the “cut” option.
First select element to be cut (Countertop), then select the family instance to cut with (Sink), and there!
In this method, if you had to move your sink, the cut (void) moves with it. Same if you change the size of your sink.
If you use the countertop family with an opening hole in it, you just have to modify the size of opening every time you move or adjust your cutting element.