As well as Avatars SDK, builder SDK items can have custom shaders on their materials.
Custom shader will only be displayed when the a parcel is not unloaded (unloaded mean the low quality version is shown).
When a parcel is unloaded, each custom shader is replaced by the default material. To be sure your items wont be white, you need to have a texture and a color with the right name on each custom shader “_MainTex” and “_Color”.
Tutorial and more infos coming soon