Box3D is a modern outperforming most general purpose physics engines at stability and accuracy, including PhysX and Rapier. This mod adds Box3D as an optional replacement for Rapier which is used by Sable.
This project is a proof of concept to show how the open source / source-visible nature of Sable and Simulated suite in its entirety allows complete bystanders to contribute to their ecosystem. This would have been a Valkyrien Skies addon if it was genuine open source software. Alas, only the Minecraft-facing part of VS2 is available, while its Minecraft-independent portion including networking is obfuscated closed source software.