two pieces puzzle

The goal is two slide in both pieces. The pieces can only go through two empty slots. The cover can make sure that's only possible way to get in. You can choose to print the cover or not. I set it separated in a plate for different material. recommended translucent so that you can see through.original ideas come from: https://puzzlescore.com/en/brands/yuu-asaka/https://www.puzzlemaster.ca/browse/inventors/yuuasaka/18654-creep-2-puzzle-original-version Boost MeFeeling impossible to solve this