My grandmother had black walnut trees. She used to collect the green walnuts and put them on trays to dry out: The "trays" were wood frames with small chicken

My grandmother had black walnut trees. She used to collect the green walnuts and put them on trays to dry out: The "trays" were wood frames with small chicken wire bottoms (sturdy plus air flow). They seemed large, but I was a child. And then, she'd wait until they dry out. When the fruit dries out, it is much easier to remove. It gets brittle and comes off. It will, however, stain everything dark. Wear gloves (they used leather), wear old clothes, and it might help to be outside. She generally got help with this. Underneath, there was just the regular walnut shell, and it can be opened with nutcracker tools. Sidenote: As a child, I hated these walnuts because I thought they were yucky. It actually made me swear off walnuts completely for some years because I didn't realize they were a different variety.