Bar Code Uses

Hi Mike,
The formula for the URL QR Code will vary greatly depending on how you want the application to work. It is impractical to place a Barcode with the URL on a tool without using a URL Shortener, and even then it still might be too long. The basic formula for the QR Code would be
"<img style=\" width:150px; \" src=https://www.cognex.com/api/Sitecore/Barcode/Get?data=" & URLEncode([QR Code]) & "&code=Z_QR_CODE&width=150&imageType=JPG&foreColor=%23000000&backColor=%23FFFFFF&rotation=RotateNoneFlipNone>" and the QR Code URL would be
[QR Code] = URLRoot() & "db/" & Dbid() & "?a=er&key=" & URLEncode([Key])
You can perform different actions inside of the URL and make it so that you can check out the tool with one URL and check in the tool with another one. The URLs will depend on how your application is going to be set up.

One of my use cases is inventorying tools. I will have a tertiary table that will have a relationship to the Tools table and a Locations Table called Inventory Records Table. Each user will be assigned a default location inside of a Users Table, and when they press check-in then it will automatically populate their location with a form rule. So, all they need to do is scan the Barcode (Tool ID), and then save it. 

I hope this helps!
John