I'm here to teach you how to make a lava fall. Take a look.
Step 1: What You Need
A good amount of glass
And I would suggest and empty bucket in case something goes wrong
Step 2: Building the Body of the Fall
Here is where the glass comes in.
Put four pieces of glass as the base.
To get the right format of the four pieces of glass, corners should be touching as the photo under this text will show. Keep building layers of glass as high as possible for your lava fall to look better and cooler.
Step 3: The Lava
Go to the top of your glass tower. Tower should not be covered up. The top should be a hole, no glass cover as in the picture below. Then just put lava on one of the towers sides, and you have your lava fall! (By the way, the suggested bucket is just in case something goes wrong when putting the lava in.)