I designed a funnel for filling different liquides such as engine oil, coolant and so on. Extra narrow throat of the funnel so it will also fit in some narrow openings of the filling caps. I recommend using some chemical resistant plastic such as ASA or PCTG.

I printed it out of ASA with 6 perimiters and 100% infill. Also I added a brim of 2mm inside and outside with 0mm offset to improve print bed adheason. I removed it with a deburring tool afterwards. See picture attached for print orientation. You should be fine with the overhang of the handle but however if you want to be safe just add the tree supports.

Have fun!