Thanks to JavaFX, the upcoming release of Assemble2 will provide you the way to load data directly from several RNA databases (i have started with the Nucleic Acid Database and RNACentral). You will be able to browse the website as you were used to it. Once on a webpage describing a 3D structure (for the Nucleic Acid Database) or a sequence (for RNACentral), a button will be activated, indicating the ability to import the data into Assemble2.

RNACentral_linked_to_Assemble2