A tool for getting garrys mod steam workshop collections downloaded locally.
Download the tool (hit 'Download Zip' button). Then extract and run console_here.bat
That should open a shiny console window for you.
Now type, for example, for the workshop url (http://steamcommunity.com/sharedfiles/filedetails/?id=619946236):
gmadget --singleids 619946236
That will download the workshop item and extract it in the gmadget folder, under the name of the addon :).
There is also
gmadget --collectionid (collection id)
that does the same thing for collections.
The tool, at first run, tries to guess where the gmad.exe file is. If this fails, edit or gmad_path_best_guess.txt with the path to gmad.exe :) And, if you can arse, create a support issue or email magnusjjj@gmail.com :)