You can create an inventory in a Bookshelf by Right Clicking on the Bookshelf.
This is how the Backpack looks like.
Example of locking an inventory
Here the the doubledoors are locked with a pincode "1234" and Autoclose after 3 seconds. The price to use the doubledoor is 1.
When you open a doubledoor, both doors open at the same time :-)
Picture of an experimental GUI interface for Digilock
This is who the inventory looks before and after sorting and stacking
Here's a photo of the GUI for the Digilock mechanism as of version 3.2.4
This is how Spout EditSignGUI looks like....
You can allow the users to have an portable workbench or let them buy one.