Frustrated with using nearly empty dishwashing bottles, the decision was made to make another one.  It doesn't fit as snugly as the paw soap, but it works.  This is 1 case where a photogrammetry or 3D capturing system would be worth it.  Another system which might work is taking photographic profiles of the bottles & scaling the photos to life size in Freecad.

The adapter needs more than 1 stair step & it needs to be an oval.