I am currently searching for a bong and I am wondering if there is some sort of adapter I can purchase to enable the easy use of a one hitter with it. 18.8mm is the size in my currently selected bong.
why wouldn't you use the bowl that comes with the bong? Put enough in there for one rip.....if thats what you want.
https://www.grasscity.com/accessories/bong-adapters They also have bongs and there are many bowls under accessories. Some are hard to determine the capacity but a lot of bowls can be ordered either 18.8 or 14.5. Welcome to Grasscity.
Buy a one hitter and a double male 18mm adapter, wrap tape around the bottom end of the bat(or drill a hole in a cork and shave down the sides) just enough so it snugs into one of the ends of the adapter. I've done this and it works well. I barely use it, because I got myself to get used to loading small snappers in regular bowls.