Methods for fabricating integrated circuits and for forming masks for fabricating integrated circuits are provided. In an embodiment, a method for fabricating an integrated circuit includes etching an upper mandrel layer to form upper mandrels. At least one upper mandrel has a first critical dimension and at least one upper mandrel has a second critical dimension not equal to the first critical dimension. The method further includes forming upper spacers adjacent the upper mandrels and etching a lower mandrel layer using the upper spacers as an etch mask to form lower mandrels. The method also includes forming lower spacers adjacent the lower mandrels and etching a material using the lower spacers as an etch mask to form variably spaced structures.