My 2020 project was to build a Voron (http://vorondesign.com) 3D printer. While it will probably always be a work in progress, it is now to a point that I can consistently print ABS.
The whole project has been such a learning process that would have been impossible without the support of the Voron community on Discord as well as watching hours of videos and live streams by Nero 3dp. Additionally, thanks to Defib on Discord for his amazing Print-it-Forward set of parts. Maybe one of these days I can get my printer tuned to print such beautiful parts.