Excellent for both 2D and 3D modeling; free for individual academic use.
If you just need to draw structures for a paper or lab report right now, these are incredible, free, and won't put your computer at risk: chemwindow 70 download free exclusive
As a peer who understands the struggle of finding specific legacy software, I have to be straight with you: is an older, proprietary piece of software originally developed by SoftShell and later acquired by Bio-Rad (Sadtler). Excellent for both 2D and 3D modeling; free
A great web-based option if you don't want to install anything at all. Why avoid the "Free Download" sites? these are incredible