This new tool from Autodesk is cool! The only thing I miss in it is to be able to download STLs directly (now it is only .obj).
Originally shared by three.js
I was never able to open STL format even with all those 3D softwares installed, seem it losing support this year.
STL is the format used by “all” 3D-printing softwares.
STL is fundamentally different than obj, it’s simpler and more compatible for them to use a more accessible format to import for your workflow.
@Eric_ErFillion_Filli you need to install an stl viewer 
stl is used by all slicing software and is the most common format for distributing 3D printable files, though I’m curious to know what will replace it for multi colours!
AMF is the new format that is being standardised. Cura (by @Ultimaker ) already supports it.
That was great tool!!
Also with Cura software you can slice straight from obj files, and still be a Beta proyect sure theirs add more export options with final realese.
@Peter_Parnes In everyone adopted AMF it might be a major advance, but are there patent or implementation issues? Currently very few applications support it.
I am not that well informed on the details but from what I have read several large companies are involved in getting an open standard for this. Well see… @YouMagine already supports AMF for multicolor models.