A 16mm six sided dice which has a hollow spherical area inside designed to fit a 5-6mm spherical neodymium magnet (these can be bought online for a 15-20 cents each). The magnet is added about two thirds of the way through the print and is sealed inside. The dice can function in space. The dice will click to any common metal surface, allowing you to roll dice on the fridge, a whiteboard or even on the side of your car. The internal sphere ensures the result is random. Please note that these dice will stick to each other, which makes them easy to carry as a single unit, but does mean you can't roll more than one at a time. I have rounded the edges to make it more robust and durable, as well as easier to roll. The dice will function normally on a non-magnetic surface.
Here is a small video of one in action on a fridge. http://tat.mithril.com.au/Magn...
I designed this for playing games in a limited space or to play when travelling. The magnets are strong enough that you can easily toss the dice up onto the underside of a metal surface to roll them. They can also be used as numbered markers on a whiteboard, fridge or similar. I used dimples to make it easy to colour the dots with a permanent marker (I have used different colours). I like the idea of someone on the ISS using these to play Traveller RPG (or similar) in space. (and I hope they don't interfere with any of the equipment up there.)
It is a pretty easy print. I print it at about 80% infill as the magnets are quite strong and I don't want the inner shell to break from impact. I use white PLA, and print at 200 degrees on a 60 degree heated bed. I print without supports, brim or raft.
I do have to be careful where I place the print on the bed in case there are magnetic elements in the printer. I don't want the magnets moving during the print.
If anyone asks, I can create a full set of d4, d8, d12 and d20. I don't think they will work quite as well because of the required size of the sides and the dimensions of the magnets, but I'm happy to try if people want.