Design an enclosure for sensor with 2x AAA batteries (IP65)

We have a project which requires mechanical input now. We design a product and looking at placing it on mass production at the end of August. The device we are working on is a simple temperature and humidity probe which has to meet IP65, be powered with 2x AAA batteries inside, also be UV resistant as it may be exposed to direct sunlight occasionally, for the indoor and outdoor use across the UK only. We need someone to be able to design an enclosure for such a probe(sensor) and generate all the production required files accordingly. Oversee the design through all stages until production samples were received and approved. There would be a number of stages requiring your involvement:
1. Concept design and 3D rapid prototype samples validation and testing (within two-week time)
2. Changes/updates in the design and files release for tooling production (injection molding)
3. Approval of first casted/injection molded samples and approval for mass production
The overall design model is not finally defined and can change depending on feasibility but we have concept drawings to start with, we also have 5x PCB prototypes which are currently being tested but will probably require updating after getting a final mechanical design model from you. If you are capable to undertake this work and go all the way along with us until the production samples were approved, please let me know. I can send you the spec and concept drawings after signing the NDA. The product is for the general consumer market and has to meet all the required safety regulations and be CE compliant, but that subject to standard manufacturing procedures as far as we concern. We have a limited budget, so hopefully, we can agree on a total cost per project and pay you in stages.
The design, as said, has to be UV and IP65 robust and look stylish – smart for use within the IoT infrastructure, but not strictly.
Thanks.