Did not suggest a 18" to him, my project alone The child can open boxes, paint parts. etc Yes, the 30mm is often sold as 1.25". When I purchased my lens at a telescope store in Irvine, Ca they were sold as 30mm. https://www.amazon.com/Explore-Scientific-Degree-Waterproof-Eyepiece/dp/B0833H56GY A cheap lens will never give the quality of a better lens. I doubt most people will ever polish a lens, or machine their own screws, or cast parts. Kits are available - get over it!