Tweak each part's material properties for customization so we can finally get rid of the tinker panel and rely on xml for more material combinations. This can apply to every parts including hinges and procedural parts.
Things that are important:
Density ¦ 16mg/cm³ to 22.57 g/cm³
Maximum Heat ¦ infinite/highest maximum limit
Collision Reaction ¦ None, explode, disconnect
Surface Roughness/drag ¦ paint property
Part Scale ¦ XYZ scale
List of material properties
Comment: i had a simpler idea but this took time to think about so this suggestion is pretty much a more detailed tinker panel but legal