If you want to do something like this as some kind of R&D mule, I highly recommend you do it in the desert where land is very cheap, sand readily available on your own property for mixing the concrete, and code enforcement is less prevalent.

Additionally, you may want to check out super adobe structures. It would be interesting to try automate construction of some of calearth's [0] designs. I can imagine a machine filling and laying the earthbags fairly easily... and IIRC some of their designs have already been certified and legally built in San Bernardino county.

[0] https://calearth.org