Abstract: A mixing device comprises a hollow drum formed by a shell of substantially constant thickness and defining generally a body of revolution, preferably cylindrical, spheroidal or ellipsoidal. The drum includes internal vanes which are defined by corresponding grooves extending inwardly from the external surface of the drum, each groove having detachably positioned therein a comb of spikes. An opening is provided in one axial end of the drum by means of which the interior of the drum can be filled with and emptied of material. A handle is pivotally connected to the drum so that the drum is rollable along a supporting surface and rotatable relative to the handle about an axis coincident with the axis of said body of revolution during which rolling the vanes agitate the material within the drum. A spraying attachment can also be provided which includes a sprayer head connected to the interior of the drum by way of a pipe.