One of the biggest challenges we face is ensuring that our body and environmental temperature sensors provide accurate readings. If they’re off, it could affect the entire system's performance. We also need to consider the limitations of our microcontroller; it might not have enough processing power or memory to handle complex algorithms effectively.

Another hurdle is managing the power consumption of the Peltier module while still keeping the water at the right temperature. Plus, all the components need to work seamlessly together, which means we'll have to put in a lot of testing and debugging to make sure everything integrates properly.

Safety is also a top priority. We need to implement features that prevent overheating or electrical issues to ensure user safety. Lastly, balancing the project cost with the quality of components and the features we want to offer can be tricky, as we want to deliver a high-quality product without breaking the bank.