diffuser panels made more simple?

I am just curious about the building a diffuser panel in a diy project. I priced many and the pricing for what looks like injection molded close cell foam forms is a little to rich for my blood. I'm asking about the forms "diffuser panels" is there a rhyme or reason to there structure? I am sure a PC model of sound waves is used to build a structure and then a mold is made. Can I just as a layman just glue different forms and then spray with a water base paint and mount or is this just a simplistic view of a more complicated structure? I thank anyone with some expertise in this and please bare with me if I am completely off track.