Yes, you can use a custom-made door to replace a standard door in your project. However, it's important to ensure that the custom door meets all the necessary building codes and specifications required for your project. This includes considerations for size, material, fire resistance, insulation, and any other relevant standards. Additionally, you should consult with your architect or contractor to confirm that the custom door will fit properly within the existing framework and align with the overall design and functionality of the space.