This is a spell card case and spell slot tracker I made for a ranger character. The magnets on the front represent the spell slots and can be moved easily from one side to the other. The compartment holds classic poker cards. I use the following two sites to create my spell cards:

https://rpg-cards.vercel.app/

https://5e.tools/makecards.html

For assembly, slot the magnets into the back of the cover as seen in the last picture above. The alternating poles are not strictly necessary, but you won't accidentally slide the marker magnet into a wrong lane this way. If the fit of the magnets is a bit too loose you can add a drop of superglue. For a level 20 ranger character, you will need 25x Magnets (d=5mm, h=2mm) as they can never have more than 3 level 2 slots for example.

When the magnets are in place, you can attach the corner pieces with some small spots of superglue. The “lock” simply clips on from the side.

I will be making more designs for different classes in the future and posting them as links down here:

Artificer: https://makerworld.com/en/models/1004995#profileId-983281

Bard: https://makerworld.com/en/models/568919#profileId-488846

Cleric: https://makerworld.com/en/models/568931#profileId-488863

Druid: https://makerworld.com/en/models/568933#profileId-488866

Paladin: https://makerworld.com/en/models/1005025#profileId-983316

Sorcerer: https://makerworld.com/en/models/568945#profileId-488880

Wizard: https://makerworld.com/en/models/540118#profileId-457481

Until then, happy printing and roll initiative!