Foam is all kinds of useful, but trying to cut it with scissors or a serrated plastic knife is usually an exercise in futility. What you really need is a hot wire for nice clean cuts. [Elite Worm ...

A foam machine can be cheap to build ... For foam fluid, most DIY builds recommend a 2% mixture of soapy water. This author found success by mixing 5 litres of dishwashing liquid with 250 liters ...