Secret Lid - Plain and Tiered.stl
The current lid gave me a lot of trouble; the pegs were hard to insert and broke off when I pried the tile open. They are also too high and left a 1mm slot between the base and the lid.
Also, the surface around the question mark tried to print a 3rd layer in midair and just made a mess. Maybe they print beautifully in Mr. Zack "Moneybags" Freedman multicolor printers but most of us only have poorly calibrated Ender 3s to resell Zack's models on Etsy.
So, I fired up Tinkercad, because apparently I can't be arsed to learn a real modelling software, cut 2mm off the pegs and made them tiered, leveled off the lid surface and made 2 versions of the question mark so you can print a lot of those and just stick them on top of the lid.
I only had time to print one but it worked great. I still think the better option lies with magnets but I had none at hand so, maybe next version.