The chlorine toilet tablets you drop into the toilet tank are great for keeping the bowl clean, but they eventually destroy the flexibility of the rubber flapper, so it starts leaking.
I designed this to fit over the top of the overflow tube, and you attach the little overflow hose to it. You place the tablets in it, and the overflow tube water slowly dissolves them, but the chlorine water never enters the toilet tank itself, so the flapper is safe.
A bonus is now all the chlorine goes into the bowl as it fills after it flushes, instead of being diluted and mostly being flushed away.
Another bonus is that the tablets now last 5 times as long.
Note that the supplied stl/gcode might not fit your toilet. You'll have to measure the tube and adjust the OpenSCAD file. Each of the toilets in my house had a different size.
Update: the toilet tablets have suddenly become a lot smaller, but you have the OpenSCAD file to compensate by making the “big end” diameter smaller.
The author marked this model as their own original creation.