The 6.4 update allows for using multiple textures (tilable even), but does cost some considerable performance. An entity with 16 skins renders as fast as ten separate (duplicated) entities with one single skin. It is still possible with the older versions, but requires laying out the textures all on a single image which doesn't permit tiling. You can do this with 6.4. Use as few textures as possible for this (especially when using small decals like numbers on a ruler or street addresses where it's much better to lay out each texture on a single skin image (to up to 1024x1024 for best results). Be sure to allow for a 4-pixel padding on all sides of the textures to prevent odd artifacts caused from mipmaps.