This is my first OpenSCAD part. I decided to start with something fairly easy, in this case a box and lid. If you have any suggestions, feel free to leave a comment.
To create a round box use the same value for width and length, then set the corner radius to half of that.
The script will always generate both box and lid. I might change this in the future. For now, you can just split the 2 parts up in Cura, then delete one of the two and print them separately.
21 February 2016 - Added option to customize section height.
You can print this with whatever settings you want. The defaults are optimized to be used with a 0.4mm nozzle, but those can be easily modified in customizer.
For a snug fit between the box and the lid, use 0.4 as tolerance. Depends on your printer accuracy. For me 0.4 was a perfect fit, but for you 0.4 might be too loose.