who will not be collaborating on it but just looking at it or using it as a base for other materials of their own.
If you want both options available (viewing and modifying), the safest and best way to proceed is to upload your books to the Bloom Library. In this way, others can freely view them online or download the .bloomd and view it on a device, or download into the Bloom editor to translate/adapt them.This of course assumes the books are completed and ready to be shared.
If your books are not yet finished/complete, then I would hesitate sharing them with others to use “as a base for other materials” because they could then prematurely propagate your text and images when in fact your text or images are not yet ready for sharing. This could lead to problems. For example, suppose you haven’t yet set credits for your images, then share your collection with others, then that person uses those images and attributes inaccurate credits to those images? That would not be desirable. Or suppose your text is still a work-in-progress, do you really want that text to be translated into other languages?
If by “use as a base”, you mean “use the structure of my book but not the actual content”, then what you want is to create a custom template for others to use using the Template Starter.