To face the variable demand of the market, modular and mobile equipment are integrated on production lines. Previous works proposed design and evaluation methodologies to build recon figurable production systems. However, taking the right decision concerning investments and the choice of equipment may be complex. In this paper, we present RAS design from a risk and decision analysis perspective to support decision making. Market demand scenarios are associated with occurrence probabilities. A decision tree represents consecutive scenarios, for which the decision maker is proposed to make a choice regarding investments for the assembly line. The utility function is computed based on the decision maker as attitude to risk. The objective function computing the final score of a scenario and a decision covers investments, recon figurability rate and performance of the system. Implications of early investments towards recon gurability can be identi ed. The approach is applied on a real use case from the automotive industry.