We have used an old windows 7 machine for this example, as most know windows 7 is now unusable as a working PC as it's lost all security updates and patchs from microsoft.
We have placed our custom built software on this PC, it locks the machine down so no user can access its user interface, it also locks the machine from the manged network it is on for extra security.
This solution gives a new life the the old hardware and gives you the client the ability to work on an up-to-date secure system.