I have a folder full of images in PDF format, and I would like to merge them all into a single PDF in which there are many images on each page, but still in vector/PDF format. The ImageMagick 'montage' command almost does this, but it actually converts them all to raster images first. I want to be able to create a contact-sheet that's still in vector format, so I could specify 16 PDF files, and it will return a one-page PDF with 16 scaled images on it.
Any ideas?