Sorry the text description is confusing. A way to do it is to lay the jug on its side on a table, handle up to one side or the other. Bracing your hand on the table, hold a marker so that its point is at the mid-level of the jug. Holding the jug firmly, side down on the table, slowly move and rotate it around against the marker so that you end up with line from the spout along one side, across the bottom, along the other side back to the spout. Cut along the line and you will have your tub with the half spout to act as a convenient overflow spot.
A half gallon cardboard carton might work as well but the smaller objects and volumes necessitated are likely to result in higher degrees of error. In either case, the sides of the “tub” will have to be supported with stacks of books or other objects
Yes, one or more photos and any comments regarding your experience with this exercise will be greatly appreciated. Can someone make a video of this? Bernie Nebel