I made this device to help destem elderberries. It's 1/2" x 1/2" hardware cloth zip tied to the top of a pet crate door. I could also have used a baking rack or anything that's sturdy. It's zip tied to a 5 gallon bucket. Then just rub the berry clusters on the hardware cloth and they fall off! I can destem an entire bucket full of berries in about 20 minutes. Otherwise it would take me well over an hour.
If you have something better that's not a $500 machine, please share!