Free and very easy: DIY a honeycomb for your flash | Flashpoint - Official Website

A honeycomb is an accessory that can control the light beam of a flash, but you don't have to buy one ready-made; you can make a DIY flash honeycomb. This will provide detailed instructions on how to choose materials, what tools are needed, what size of honeycomb is appropriate, how large the cardboard strips should be cut, and the order of making the honeycomb along with precautions. It also includes photos for detailed explanations. Additionally, there are instructions provided for installing and using the honeycomb.