I have a no-peek device that turns red if the dealer has blackjack, otherwise turns green. I'm sure most of you know what I'm referring to without a photo. I'd like for someone way smarter than me to look this thing over, along with the (expired) patent paperwork to see how hard it would be to build. If interested, please PM me. I'm willing to pay a little bit for your time and effort.
Image: https://www.kardwell.com/nopeek21.html
Image: https://www.kardwell.com/nopeek21.html