In Thailand, the effectiveness of tsunami evacuation measures has been evaluated and improved by drills. Crafting is the activity of skillfully creating something. Effective tsunami evacuation measures can be crafted with the advancement of computer modeling and simulation. Various tsunami evacuation simulations have been developed and adopted in at-risk communities worldwide as alternative solutions to evaluate and improve tsunami evacuation measures. However, the interaction of evacuees with the environment (e.g., signage) and gathering behavior have not been investigated in the tsunami evacuation modeling. This paper introduces a multi-agent simulation of tsunami evacuation for crafting effective tsunami evacuation measures. The simulation was created using the Unity3D game engine, which has a scripting application programming interface (API) for the navigation system and physics simulation that is crucial for evacuation modeling. To develop the evacuation logic models and inputs, questionnaires and field surveys were conducted. A case study of the model is demonstrated in Ban Bang Niang in the Khao Lak area because it has flat terrain and economic (tourism) growth, which can contribute to higher tsunami risk, whereas it has measures to reduce the risk of tsunamis in all dimensions. Twelve scenarios were designed to evaluate the effects of different tsunami evacuation preference ratios. The results of sensitivity analysis show that evacuation rates were responsive to gathering behavior ratios, vertical evacuation ratios, and signage follower ratios, respectively. Finally, effective tsunami evacuation measures can be crafted with the combination of officially announcing the existing tall buildings as designated evacuation shelters, pinpointing them on the maps, and minimizing gathering behavior.