Caffeine is a molecule, and I designed it such that you can put a coffee mug on it.
This was inspired by what I saw on thingiverse, so I made one which I liked best, this is version 6 actually. Sketchup was used to made the 3d model and to convert it into stl, and the PP3DP up printer software printed the stl file. Earlier versions did not have all atoms indicated by letter, this one does, hydrogen is skipped because you often do in chemistry. But it is also a nice high school exam question, such as, what is the weight of this molecule and where is the hydrogen? Have fun.