I was then challenged on Google+ to prove it was possible by Kids Chaos, Cathy Ranson of Netmums and Paul Stickland - the author/designer of some truly amazing children's books.
You can't ignore a challenge, so I set my teenagers onto it!
We took a standard postcard as a template and cut cereal boxes to size, and then made the slits in much the same way as Kids Chaos explained, but more finely.
And then.....step through it!
They did a great job - and I had to pay out 3 packets of Swizzels Rainbow Drops as prizes!
What is the smallest piece of card your children can step through?