We'll have an advent calender again this year, same as in the last years, doors open at midnight UTC. https://openscad.org/advent-calendar-2023/ Also as in the previous years, we don't have all the doors filled yet, so if you would like to help out, reach out to me or drop into the IRC channel. There's no fixed rules, but (if possible) the guideline for the models is to be - small and self-contained - licensed CC0 (basically public domain) - have a square preview image (e.g. 800x800 pixels) If the model is printable, even better. ciao, Torsten.