insert for card decks removal

The longer variant raises the deck, take it out just by pushing on the slope. There's also a shorter variant, raising just half of the deck.

This insert also prevents cards from sliding into neighbouring compartments.

I exported stl for 57,5 × 88 mm, you can use the included FreeCAD file the get the right size for you. Just change the parameters in the spreadsheet. Or text me with your desired dimensions and I'll add it for you.