I don’t think there exists one on lemmy right now. I would recommend thinking about starting your own. You can have discussions about it here, but that’s not really our focus and it would probably be better to create a dedicated community for it.

Edit: Having said that, there are a bunch of Blender communities. As well as a FreeCad community. Take a look at https://lemmyverse.net/ and see if you can find a community that fits what you need, perhaps one that you can help revive.