This is my designed MTG Commander Deckbox.
You can fit up to more than 120 Card with sleeves and some dices as showen in the pictures.
The magnets i used are in this version are round 12x2mm.
The hardcover showcase (toploader) card is 3"x 4".
https://www.amazon.de/AMIGO-81222-Toploader-regular-Fix/dp/B004KHV24W/ref=sr_1_6?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&crid=72T1XYJOU93D&keywords=top+loader&qid=1706113465&sprefix=top+loade%2Caps%2C89&sr=8-6