Game1part.cs

            //Goes into OnContentLoaded()
            
            MaterialGroup material = (MaterialGroup)_boardGroup.Find<Surface>().Material;
            DiffuseMaterialPart materialPart = (DiffuseMaterialPart)((MaterialPaintGroup)material.MaterialParts
                .First(x => x.Name == "ground").MaterialGroup.MaterialParts
                    .First()).MaterialParts.First();

            _boardTexture = materialPart.Texture;

Scene1part.xaml

            <!--Goes into Surface
            Remember to delete the BasicMaterial!
            -->
            
            <MaterialGroup>
                
                <MaterialPaintGroup.MaskTextures>
                    <Splatter>
                        <ExternalReference />
                    </Splatter>
                </MaterialPaintGroup.MaskTextures>

                <MaterialPaintGroup Name="ground">
                    <DiffuseMaterialPart Texture="{ContentReference Assets/MainBoard}"/>
                </MaterialPaintGroup>

                <!--Fixes mysterious null reference bug. Should investigate later.-->
                <DeferredLightsMaterialPart />
            </MaterialGroup>