Lets say you want to have some pattern displayed within the bounds of a shape, as the blobs are to this rectangle. There are a number of ways you can do this in Inkscape, with crops and masks etc, but I’m going to show you a far more effective way that allows you to resize the shape, without having to worry about re-cropping the pattern.
Lets start with our two objects, a blobby object and a rectangle below it.
Crate a clone of the rectangle (Alt+C), the cloned shape will appear on top of the others. A cloned object is linked to the original, so any changes you make to the original will also happen to the clone.
Select the cloned rectangle and the blob object (Shift + Click to multi-select). Then clip the blobs with the clone (from the menu select Object > Clip > Set). This will only show the portion of the blob object that is covered by the cloned rectangle, the cloned rectangle itself will become invisible.
Now you have the pattern displayed on the shape. But more than that, you can resize the rectangle and the pattern will expand to fit it!
TaDa!!!
