I would actually choose an example that seems to be not complex and slowly drill in to show the opposite. As a software tester I would suggest just that- build

I would actually choose an example that seems to be not complex and slowly drill in to show the opposite. As a software tester I would suggest just that- build together kind of a test plan, slowly add layers to it and while doing it demonstrate bugs that were find in different places. Even the simplest web site can result in huge number of tests if you go low level enough, networking, servers, disks, backups etc.