What is the best free software to draw different experimental schematic diagrams and crystal structures manually??
For example,
(1) I want to draw different crystal structures like cubic, tetragonal, hexagonal etc. manually, and
(2) I want to draw a schematic diagram of a whole experiment, for example, the schematic diagram of the preparation of thin-film Perovskite Solar Cells or else.
Thanks for your precious time and suggestion in advance.