When my sons were playing with their duplo bricks in the shower it was always a hussle to remove water from them.
Started searching foe a different design on 3d sites but they were all with sharp corners and/or needed support for printing so coded this duplo compatible brick generator and I can generate any size of bricks now. This is only one example, happy to upload other sizes that you need. Just leave a comment with the size of the brick in the format of x/y/z (Example this brick: 2/14/19) and rate the profile and I will add a new print profile for you.
You shall not share, sub-license, sell, rent, host, transfer, or distribute in any way the digital or 3D printed versions of this object, nor any other derivative work of this object in its digital or physical format (including - but not limited to - remixes of this object, and hosting on other digital platforms). The objects may not be used without permission in any way whatsoever in which you charge money, or collect fees.