For varying reasons, some 3-D modelers banned their masks from being used in the contests. Because of that, only modelers that gave their permission may be used.
6d. At this time, the only 3D modelers who have expressly allowed the usage of their pieces are KingSidorak, Galva_, GX_05, KhingK, Vahki6 (for him, check this post), D-S-Creation-Forge.
I don’t know who made these masks, so I can’t confirm.