Base Material Determination, Polymer vs Metal

Base Material Determination for Structural Use

I am looking for a freelancer who can help me determine the ideal base material for a structural application. The material needs to be strong and durable, while also being low-cost.

Requirements:
- Determine the best base material for structural use
- Material needs to be low-cost
- Material needs to be strong and durable

Ideal Skills and Experience:
- Material Science or Engineering background
- Experience with base material selection for structural applications
- Knowledge of low-cost materials that are strong and durable

Intended Use:
- Structural

Budget:
- Low-cost

Please provide a proposal outlining your experience and approach to this project.

I need to understand what materials will meet the needs for my project from a structural as well as a cost perspective. I have some design considerations to resolve and unable to move forward without understanding which materials and thickness will meet my needs. For all in intents and purposes, it's a pipe structure and I need to create custom connectors that will have to molded. I need to know what material can meet the stress requirements so I know how best to proceed with my project. If you're able to help me resolve this, it will leave open the possibility for additional phases of the design work for this project. I will also be designing it to attach an index plunger to attach and another clamping device (not part of this scope), but need to know what material I can get away with for commercial use. The pipe running horizontal (picture attached) will be 40 inches in length and 1.25 inches in diameter (steel tube or custom aluminum extrusion TBD) Needs to withstand approximately 300-350 pounds of pressure applied to the end point of the bar with minimal flex. I need to know what material can help me achieve this, preferably .125 thick but no thicker than .25. I'm open to materials that might require design alterations in order to meet the structural requirements (i.e. thicker supporting the base). It would be helpful if the material could be 3D printed for creating and testing various components. I would foresee this part having to be injection molded or cast.

I added another picture that represents a similar product for reference. I need to create a similar component that will allow me to attach two bars together. As stated earlier, I have a few different design considerations that will allow for securing this piece through an index plunger, however, that is not part of the scope. I don't need anything complex, merely something that might be used in SolidWorks to show structural integrity of a proposed material. I'm not sure if there is something less costly than something like carbon fiber or having it cast in aluminum, but given that it will be produced commercially, cost is definitely a consideration.