This is part of the series of 30 exercises developed during the 3D4KIDS program. Onte of the aims of this Erasmus+ program is to improve the knowledge of teachers regarding the 3d printing technology by developing some specific training materials. More info in the website: https://www.3d4kids.eu/ This activity is about designing a 3-sided die, figuring out what its shape could be and printing it. After that try it in order to check if its faces are equiprobable. 2 example models are given.