Welcome to the forum dcap.
There are many threads on this you might like to look through .
Just type in ..payload drop ...in this Google Custom Search
( type in the middle not the top ) and you will see what you might be looking for .
I figured out how to make a pretty legit one. I bought a lid switch for a washing machine and fastened it to a bracket. I’m wiring it up now. I’ll post more pics and info when I’m done.
I was going down the same path as you when I found this drop device below. Simple, elegant, and pretty slick. It works perfectly on my P3S. He's working on improving the design for P4's.