A 3D unity example scene of CptPotato's 3D smooth pixel filtering, same algorithm as 2D same algorithm as 2D but now in the standard shader so 3D objects are shaded correctly.
To get the filter on your 3D objects set the filter to bilinear filtering on the imported textures under the advanced tab, import your 3D objects and apply the 3DSmoothPixel shader to your material.
an Example: