Set page size for the output

As I understand, this tool is primarily used for projecting. For projecting, the final size of the output is irrelevant.

However, I think this tool is also awesome for assembling an A0 page from multiple A4 pages. It's faster, easier to use, and more accurate than any other methods I've known. However, there is nothing in the tool that allows users to set the output's dimension.

Are you open to a feature for configuring output's dimension? My main language is Javascript, but I can take the time to help.