BlueSkyPlanBlueSkyBio offers a robust software called BlueSkyPlan. It is free to download and use for design. You only pay a small fee when you want to export a surgical guide or a model for printing. This "pay-per-export" model is much friendlier for small labs or beginners.
, a powerful feature within the software that allows users to manually sculpt dental restorations: Freeforming - exocad Free Exocad Software
While you can't get a full Exocad suite for $0, there are several legitimate pathways to access Exocad software for free or at a reduced cost, depending on your use case. depending on your use case.