Best appreciated by fans of the self-styled and the well-meaning, Artomatic is a crowdsourced culture fair that’s been affronting art snobs for 25 years. The latest edition is the 12th of the irregularly scheduled event, and the first since 2017. It fills an empty downtown office building with the work of nearly 800 artists and artisans, some of them well-established but many without a chance of a professional career. Most are local, yet such far-flung countries as Ukraine, Romania and Cameroon are represented.