It is possible to create floating scaffolding by:

1. building scaffolding up so it is not near any other blocks (or getting rid of nearby blocks)
2. going to eye-level with the highest scaffolding block
3. rapidly building scaffolding on the sides of the scaffolding while strafing around the structure (floating scaffolding will start to appear when it should start falling)

A lot of the scaffolding will fall, but by holding the right mouse button, a floating scaffolding is created about once every 15 seconds.

Floating scaffolding will not support the player.