That got me started. Awesome.
I have a website, and I'm totally at home in PHP, but not so well versed in JS (yet). I've never done any web API jobs, so that one will be new for me. I've done programming in Joomla, which also uses an MVC structure. Laravel looks awesome, I'll give that a shot.
One question remains, though. Since I don't need 3D graphics in the browser, do I actually need WebGL?
It sounds like I can just use PHP and the magic of regular expressions to edit the STEP file code directly, and then create a "text" file with that content. If this is the case, I'm not going to need webGL and strictly speaking not even any JavaScript. Is that right?