I am also modding the existing one right now, but with only the step files without the sketches it is quite a challenge. I hope I will have an existing prototype by the end of the week. I actually outsourced it to my brother, as he is better with the autodesk design system

maybe we just design a whole new one, although the existing tensioning system is quite attractive
The plan is to move the hemera up a bit, to have some space for the lower 9mm belt so it won't collide with the X slider. I am planning to use the volcano hotend, so this shouldn't be a problem. Also I am not going to use the Berd Air system for the moment and just some usual fan duct and so I also need a different BlTouch mount, but this just easy parts to make.
My build is actually quite progressed, the whole system is moving and I can use all the fancy bed leveling. I found this HD12 dummy carriage and this is actually nice to play around with the HD9 until I have the hemera carriage ready.