Milk Jug Cap Coupler

I wanted to make a funnel to fill a 1 gal milk jug with "ice melt" (or sand or anything else). I cut one milk jug in half, using the top as the funnel.
Then I needed a coupler to screw the funnel into any other milk jug.
Your "cap" was perfect - I just duplicated the design, inverted one and placed it on top of the other, union. Then made a 34.5mm hole through the center to create the finish.
It worked perfectly - using either the smooth or ribbed design. I then improved it - the walls seemed a little thin, so I added a 1mm cylindrical sleeve on the outside to make it slightly thicker. The latest STL files are here. They take about 1 hr to print at .16 dynamic resolution using CURA.