Without any external tools (there are plenty but maybe not worth installing, depends on you), you could use windows explorer with its "extra-large icons" view options (from the view menu).
To process those files in a separate window/monitor, you can
- Copy the images from their original location
- Open a new Explorer window in a temp directory, displayed as "extra-large icons"
- Right-click > Paste shortcuts in this directory
- work with the shortcuts in the temp directory
- When done, do the merge by hand
If you need a more complex tool, there are plenty that you can download a demo from