So I made a replacement lid for the FooGo thermos and someone mentioned that their button broke on their thermos lid. Here is a replacement button for such thermos lids. I have printed this several times and in several different orientations. I would recommend printing as it oriented in the model file and use support to support the bottom of it. Any other orientation I found was weak. Also I recommend printing with 100% infill (a total solid) using 0.1mm layer heights. I got the best results with those settings.