There are some ways to FDM 3D-print transparent plastic, see https://www.printables.com/model/15310-how-to-print-glass as one example.

Another example is this one where the 3D print was done as a continuous printing (i.e. no slicer, or sorta like a vase mode print) to make the clear show a bit better: https://m.youtube.com/watch?v=2Sy50BrlDMo