Build 12" Plano-Convex Lens

I need a single plano-convex lens, 12 inches (≈30 cm) in diameter, moulded from plastic. The curved face should deliver a long focal distance so the image keeps forming over an extended range—similar to what you would see in a modest telescope—while the flat face will be the viewing side in my custom microscope setup. Cost control is the driver here: I am willing to trade extreme magnification power for an economical build. If your process or design tweaks can hit 2×, 5×, or even somewhere in between without pushing the price up, I am all ears; “cheapest workable alternative” is the guiding brief. Please respond with: • Your proposed fabrication method (injection moulding, cast acrylic machining, etc.) • Expected focal length and tolerance you can guarantee for a 12" diameter plastic lens • Rough production timeline and any minimum order quantities I will judge success by surface quality (no significant striations or bubbles), focal consistency across the aperture, and overall affordability. Looking forward to hearing how you would tackle this.