Interestingly, PTC is now offering a free download of CoCreate personal version. As you recall, not long ago, PTC -- well known for inventing history-based modeling -- purchased CoCreate, an explicit or non-history-based modeler. PTC says the download provides the world's first free explicit 3D CAD software. Users work directly on geometry they want to modify and can design models with no upfront engineering. This helps to create lightweight designs fast.