Yesterday I was building and awesome princess plane in Duplo. However I was missing one 2×1 brick to finish the perfect model. Awesome, I 3D printed it.
This print is based on a custom Duplo brick model I made with OpenSCAD. It is not available by now since it is a work in progress. Bricks fit well with original Duplo ones.
Important remark: Printing Duplo bricks does not allow to save any money since plastic material necessary for a standard brick is the exact same price as an original one (not counting electricity, printer cost, failures, …). However, It allows to print non standard bricks and custom models.