solid objects can be composed of a set of faces that enclose a volume when combining objects within the cad system the combine tool takes user selected solids or surfaces as inputs and delivers a single combined solid or surface as an output when splitting objects the combine tool takes a first user selected object as the u201c target u201d object and cuts it with a second user selected object as the u201c cutter u201d object the combine tool delivers multiple objects as outputs the combine tool also lets a user easily merge objects by inferring a merge operation if the user selected multiple objects either by selecting a group of objects all at once or by selecting a first object and then additional objects individually when splitting a solid with one of its own faces the split body tool takes a first user selected face as an input infers the target solid from the selected face and cuts the target solid with a cutting surface based on the selected face the split body tool delivers multiple objects as outputs when splitting a face by another face the split face tool takes a user selected target face and cutter face.