VeXell

Simple attachment widget that uses native WordPress upload manager to add files link widgets to your site.
<ul>
<li>Title and Description</li>
<li>Attach Existing Files</li>
<li>Upload New files</li>
<li>Sort files</li>
</ul>
<h3>Documentation</h3>
Press “Add attachment” button. Upload or choose exists file. Add title or description for file. Press “Insert Into Widget”. 
To remove attachment press “x” link.
At any post or page you can use shortcode [widget_attachments] to display widget content. 
Available params: 
 id – Widget ID (You can see at widget) 
 limit – How many items can be showed
Example: [widget_attachments id=”3″ limit=5] It will show 5 attached files from Widget ID equal 3;

Attach Files Widget

Simple attachment widget that uses native Wordpress upload manager to add files link widgets to your site.

ryanpcmcquen

Makes local copies of all the linked images and pdfs in a post, adding them as gallery attachments.
Source & support:
https://github.com/ryanpcmcquen/import-external-attachments
<h4>Credits</h4>
This plugin is based on the work done in the “Import External Images” plugin by MartyThornley.
https://github.com/MartyThornley
HTTPS support added by IvanDoomer: 
https://github.com/IvanDoomer
PDF support added by bengreeley: 
https://github.com/bengreeley
Most of the JavaScript was rewritten from the original plugin, to reduce the 
number of global variables.

Import external attachments

Makes local copies of all the linked images and pdfs in a post, adding them as gallery attachments.

Attach Files Widget vs Import external attachments