We bring together concerns in software design and learning theoly through creation of a Java framework for development of software construction kits. The kits ate highly visual and highly interactive, and are premised on the notion of "microworlds" as environments for learning and learning research . Usage of four existing kits is informing development of the framework, which in turn we are applying to development of a new kit. The kits support construction of two-dimensional, graphical structures that behave in characteristic ways when activated. We employ design heuristics of "object permanence," "transparency," and use of multiple simultaneous views to illustrate shifts of scale, perspective, time, and representation. Broader use of the general "Kit4Kits" will help us address viability of our "elements and operations" design approach.