Attention Investment is a model to help the designers of end-user programmable systems understand the cognitive drivers for users deciding how to interact with their products. We present the Attention Investment model through examples drawn from an actual design project. This project is developing new functionality within Forms/3, a research test-bed for a concept called "end-user software engineering". As the examples show, our experience is that Attention Investment provides a useful design tool for the development of end-user programming features.