If you've ever made sandcastles with your kids, something like this can be easily achieved with some simple molds, some sand and cement and a bit of cement dye. And they're very durable. I made these over thirty years ago.
https://www.youtube.com/watch?time_continue=3&v=mtMvrgFiUkM
https://www.youtube.com/watch?time_continue=2&v=DPYMX3zjO3w
https://www.youtube.com/watch?time_continue=3&v=mtMvrgFiUkM
https://www.youtube.com/watch?time_continue=2&v=DPYMX3zjO3w