A 3D dispensing apparatus and method. The cavity wall assembly includes a masonry wall, an adjacent inner wall, a wall cavity therebetween, and a free-standing elongate strip of openwork material located within the cavity forming a debris collection surface a spaced distance above a base surface of the cavity. The harvester has a telescopic boom with a mobile portion terminated by a clamp able to move in horizontal and in vertical translation towards and along a tree trunk. 01 gm2 of the cationic polyelectrolyte comprising amidine moieties, and at least 0.