Estimators display a diversity of approaches to their task of predicting the cost of a construction project. To design and build individualized, computer-aided estimating software products to reflect this diversity is however expensive. This paper describes a new method of designing and building such products which is quick, easy and hence inexpensive. The method relies upon embedding a core estimating product into a set of software tools which can be used to reshape and enhance the core functionality. The tools have been designed to minimize the requisite technical knowledge of the user, principally through the use of declarative features. The individualistic nature of estimating is therefore reflected in this new method of developing estimating products. These resultant products are therefore more acceptable to practising estimators.