I created this for PCDB and also posted at UC, duplicating here for all of you. It does require that you have your collection loaded in PCDB,
signup here.
You may have seen the PCDB image stiches/collages that Rhu created for 2014 decks, etc. There is also talk of eventually allowing people to download their collections easily.
However, what if you wanted to create your own image collage of your collection NOW? It's easy.
1) Go to your PCDB collection (suggest using collection view that has largest images)
2) Save the entire page (on windows in Chrome just right click on white part of page and select 'Save As', then be sure to use the 'Webpage, Complete' option)
3) Locate the saved files, sort by file type and remove all non image files. You now have your entire collection in individual image files!
4) Use software of your choosing to generate a single collage from these source files.
For downloadable programs I found
Picasa to be the best free option, although
Shape Collage is pretty great as well except it adds a watermark for free version. For online
http://www.getloupe.com/ has the most options, but it adds watermarks for free version as well, leaving us with
http://www.collage.com/ as the best free option. Most others I've seen are limited to around 20 or 100 images which would only work with small collections.
More examples here from these and other solutions at
https://www.dropbox.com/sh/nzs762s2p0unxxm/AAD9dNhyKDKMADE50kXcAYkfa?dl=0 that also make it more obvious of the source, but here's a few of each to give you an idea of what is possible.
There's a few tricks for each solution (for example, Picasa needs setting change to be able to even see the small photos, layout tricks, etc). If anybody needs help let me know, but this is pretty easy stuff for most if you are willing to spend a little time.