Continuing with the previous post, when we talk about what Forge is and what you can do with it, the best way is to see demos. Many of samples shown in the recordings in my previous post are available for you to try out yourself.
Free viewer site. You can give it a try with your favorite model.
Forge Viewer UI customization sample. Click on one of sample models to load. Try full screen, auto-rotate and explode mode, and see what happens.