I just received a glass penetration / penetration frame in a box of magic from an estate. Believe it or not, I don't know how it works. I can do big illusions and know how David Coppertone vanished the statue of Liberty, but have no idea how to unlock the plastic sheet in this frame. Can you help me out? Thanks, Jim

I would think place a playing card or piece of paper in it then slide away .

Assuming it's a locking model, slide a playing card under the center plastic bar on both sides. That will unlock it and you can slide the plastic so the hole moves to the center.
Great trick!

I bought one of those little frames as a boy. I forgot about the clever locking mechanism which in itself. reignited my interest in Tenyo items.

Thanks - what a simple solution! If I had just continued, I would have figured it out! Great idea. Jim

The trick is designed so that two playing cards are used: one placed under the center plastic divider on each side of the plastic. It was originally marketed by a guy named Krug in the early 1930s (it shows up in a Mysto Magic set in 1933), but it was invented by someone else I've heard. The original models are made of metal and glass, not plastic.