The development of a Scan2PDF functionality is already in the PDF Explorer TODO list, and soon I will take a look at it.
I'm sure I will be able to reuse code and add this functionality to PDF-ShellTools, as the tool will be able to acquire images directly from Twain sources, but also use already available image files.
At least, merge to/create PDF from raw image files will be a possibility this code will help to develop.