This is a simple funnel for the “Ball - 1 Quart, Wide-Mouth Mason Jar”.
It fits snugly inside the opening of the jar, but can still easily be removed.

I printed in PETG, but you could certainly print in another material if you'd prefer.

Feel free to remix this if you like, I included the .step file in the downloads so you can open it in CAD to more easily modify it without tessellation issues.

Let me know how this works for you!