I always wanted to create a liquid soap container that was not store bought. I bought some Erleynmeyer flasks and wanted to put a korktop. But korks are quite expensive to get and sometimes their size isnt ideal. So I thought that I can design one. So here we are, two different tops, each in two varieties. one whole and one with a pump hole for the liquid soap pump. the first is designed with a bottom diameter 31mm (a little bigger to accont for the ABS shrinking) and a top diameter of 36mm so it fits every flask with the same characteristics The second one has a bottom diameter of 22mm and a top of 35mm I also posted the freecad file so anyone can change the sizes. in the freecad file I also have a stand for the shperical flasks. print your part and as it is still hot try to fit it in the flask. even small varations and shrinkage can make a cap unusable. adjust in freecad accordingly edit 13/7/13 I also made a cap for wide sized flasks, around 42mm diameter and experimented quite a lot with all sizes. The diameter of the erlenmeyer flasks is not so tightly adjusted so in the same brand and even in the same batch you can have a good fitting in some flasks while on others can be bigger or smaller. You can just mix and match and then print wider/narrower according to what you lack. A trick I found in order to counter that is to tap the cap on the flask while it is still hot. That way you ensure a nice fit, even though as it cools down it will shrink a bit more. thats especially true with pla, as the pla tends to shrink more than the usual 1mm of the abs shrinkage