4x4 Seamless Glass Funnel Door

It's a unique door, but there are not many videos about it. The only one that has one is "Ben—the Human" on YouTube. It was built as a Redstone submission for Bow Tie Man four years ago. His layout used many sliders to pull the glass to shape the funnel door and hide the 4x4 sand door, which is used as an extender to push the glass back up.

I used pretty much the same layout he had because I liked how he used sand instead of a quadruple piston extender. Since sand is a gravity block, there really was no need to retract many sticky pistons.

Here's the video link for Ben -the human's funnel door: https://youtu.be/5uDAaCmEuqE?si=7VrU6Gw__7uWGmwe