I present to you drum roll a super cool Randomly Generated Zen-Garden! 

No generated Zen-Garden looks the same, every single one is unique. 

Thanks to @Anachronist who put a lot of effort creating a OpenSCAD script for random procedural weathered fractal terrain generation. I used his code, removed everything I didn't need and tweeked around the variables a bit. Cool thing is - you can set the size of your zen garden! It can be super tiny 20mm x 20mm or super huge like mine at 200mm x 200mm.

Since I'm a complete open scad noob and spent hours trying to get a box generated around the Terrain I've given up on that mission and now they are designed independently. But let me sell it to you as a feature! 

You can have a cool vibrant color on the outer box and a relaxing darker tone as your Zen-Garden Inlay! If you ever get sick of your old, borring terrain you can simply print a new, awesome, great and RANDOMLY GENERATED Zen-Garden Terrain inlay! 

As you can see on my model demo images the box of my terrain looks quite rough. Thats because my printer died while printing :) 
But because I wanted to present to you my idea and haven't had the time to print it again I just left it like this, sorry! I guess the idea is clear anyway! :D 

I've printed the Zen-Garden inlay without bottom layers and with a grid infill. This saves filament and time. Since the inlay is put into the box the layers are not needed and the print is still fully stable. 

The tolerance of the box cutout was set to 1mm so the inlay fits better!

I hope you like my idea and excuse my sloppy print! :D 

Have some fun with it! :)