Here is one for a BB gun that could possibly work for a nerf gun: https://www.hometalk.com/8383720/diy-bb-gun-target
Hi Tom, nurf guns are so much fun and safe. Hope this helps you. DIY Cereal Box Nerf Gun Targets and Free Template -
Jul 27, 2017 - Grab your Nerf guns and get ready to take aim at your new homemade cereal box targets following our easy directions and using our free target ...
Hi Toni, here's another hometalk tutorial that will show you how to make a target https://www.hometalk.com/6139739/how-to-build-a-bb-gun-target
A simple way is toilet roll holders. Or make your own target.