AMA: Long-time DU lurker and democratic supporter, know everything there is to know about bitcoin

[Ms. Toad]

82. Your IP classes did not serve you well.

Fan art is a derivative work of an original work which is protected by copyright, and it is is most certainly infringing to create and distribute. So is creating a 3D version of a 2D work. The fact that fan art exists and is distributed relatively freely is only because the owners of the copyrights have decided it is not in their best interests to try to quash it, or pursue infringement claims.

Trademark doesn't "forbid the sale of recognizable products and materials." It forbids using a source identifier (which is what a trademark is) in a manner which would confuse a consumer about the source of a particular product. A trademark is an adjective which serves as a source identifier for a particular version of a product. For example, there are lots of manufacturers of ibuprofen. In the phrase Motrin® ibuprofen, the "Motrin" identifies McNEIL-PPC, Inc. as the source for that particular version of ibuprofen. It would be infringing (essentially unfair competition) to use the mark Motrin with ibuprofen from any other manufacturer, because that would confuse the consumer as to the source of the ibuprofen. In the instance of trade dress, what is prohibited is using a look and feel which identifies a generic product as having come from a particular source - for example, the bottle shape which identifies a cola beverage as having come from Coca Cola, or the three spokes in a circle emblem which identifies a car as having come from Mercedes Benz.

I don't know which specific case you are referring to, but the way you've described the law isn't accurate. From the cases I can find related to Battletech (none of which mentioned 3D printing), there were licenses involved, questions of waivers, and affirmation in at least one of the cases that both trade dress and copyrights existed.