Newbie questions - Audible Sensor for canning line

Hi all
I am new to the forum and have probably an odd question.

I am one of the owners of a small brewery and we have a canning line. The canning line has a 3 foot tall stack of lids for the cans that drop down one at a time. Its basically a big tube with lids stacked.

We have to monitor it visually all the time to make sure it doesn’t run out of lids.

Is there a way to build a sensor that would detect (laser) when the lids were running low? Something audible is ideal.

Attached is a rough drawing of it

Just learning about Arduino so any help on what is needed (without acronyms) is greatly appreciated!
Cheers
John

Easy.

You can get this for your sensing of the lids. You can then sound a buzzer like this or this, when the beam is sensed.

How loud does the alarm need to be?