There’s now a powerful software library available to build web-based 3D tools.
verb is “A CAD Library for the Web”, described as:
Web programmers reading this will understand immediately what verb is and what it means. But for the non-programmers, let’s just say it’s a set of free software from which you could build a web-based 3D modeling tool or 3D viewer. The availability of this software makes it much easier to do.
Sure, there already are such services, like Tinkercad and others. But with the free availability of a powerful software package like verb, we may soon see multiple other new services appear.