I bought some of these assembled notes from etsy. For the price they're quite nice, but the private keys can easily be read with a light, so they should not be loaded.
I never intended to load them so never even really tried to see if they were secure, so good to know that you did.
maybe I will take some pics of this as I have 9 of their notes and send the pics to them. This should have been something their R&D / QA people should have picked up on.