"Alexthemoviegeek" brings us a detailed look at how he created this impressive Cthulhu costume.
It's not a Hollywood-level creation, something he readily admits, but it's still quite a piece of work. To be honest, these photographs taken in bright sunlight do it a disservice. Even multi-million dollar movie animatronics benefit from obscuration. No one is better at creating practical creature effects than the masters at the Stan Winston Studios, and you'll see them using dim lighting and atmospheric effects to cover up a multitude of sins in films like "Aliens" and "Jurassic Park".
Something like this serves as a good baseline for what an amateur can accomplish with even limited materials.