In fact, the command I posted in the original question was applicable to a wide range of situations:
find ${PWD} -name "*.pdf"| xclip -i -selection clipboard -t text/uri-list
the only requirement is for the first command (find in this case) to generate a list of absolute filenames to files which need to be copied. If you check man find, you'll see that you can modify the command to find files created later than particular date, larger than particular size, having particular permissions, matching a particular regexp etc.
If you want to have a short-cut command for a particular use case - e.q. copying files from the current directory and below matching a particular mask, you can write a short script:
#!/bin/sh
find "$PWD" -name "$1" | xclip -i -selection clipboard -t text/uri-list
and call it with
cb "*.txt"
(where cb is the name of the script)