0. Download Blender

https://www.blender.org/download/

First Option

1.1. Download Chimera

https://www.cgl.ucsf.edu/chimera/download.html

1.2. Open a PDB file using Chimera

File -> Open I will use a random file (https://www.rcsb.org/structure/5ZG3)

1.3. Export to .x3d format

File -> Export Scene Make sure .X3D is selected

1.4. Clean the default Blender environment

It should look like here - if not, right click other elements and delete them

1.5. Open the .x3d File in Blender

File -> Import -> X3D

1.6. Export to .obj file

File -> Export -> .obj

1.7 Open the .obj file with Unity

Drag both the .obj and .mtl file created in the last step, result:

Second Option

2.1 Add the Atomic Blender - PDB to Blender

File -> User Preferences -> Add-ons Search "atom" and check the box labeled Import - Export: Atomic Blender - PBD

2.2 Follow steps 1.4 to 1.7 with the following changes:

In step 1.5 select PDB instead of X3D, result:

Other Option

Using code from: https://github.com/bam93/UnityMol-Releases , under ParsePDB Provided by a free software license - we can use and modify it (as long as we provide a credit)