Got lots of stuff on your desk? No problem! The pen holders tile, like a honeycomb, into a structure of any size.
The .scad file allows for easy customization if you require other dimensions. As is, it's a pretty big piece (15x15x6 cm). I used the .8 mm nozzle and .5 mm layers to make it print in reasonable time on my Ultimaker 2+. There are no fine details so that worked fairly well, but you can see the coarse layers as stripes on the walls. Looks kind of nice, though. You might be fooled into believing it's intentional.
I think it looks like the warning sign for ionizing radiation. And it sounds cool. Brings a bit of hazard and excitement to your desk :-).