As far as I am aware, and as long as the model and textures used are your own work and have been produced by legally owned software, there is no restriction on selling them in any 3d file format.
The only file format with "caveats" I know about is the .mp3 for sound.
I'm sure there are a few more examples like that but none for 3d file formats I'm aware of and certainly none for the .b3d or .x formats.
You will see that nearly all model packs are sold in most standard formats without problem.
The only file format with "caveats" I know about is the .mp3 for sound.
I'm sure there are a few more examples like that but none for 3d file formats I'm aware of and certainly none for the .b3d or .x formats.
You will see that nearly all model packs are sold in most standard formats without problem.