This card holder is approx. 31cm wide and has a secure stand. 
The cards fit in easily, both vertically and horizontally. 
To protect the cards and for a better feel, all edges are rounded. 
With 49g PLA, it is relatively material-saving and yet stable.

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Dieser Kartenhalter ist etwa 31cm breit und hat einen sicheren Stand. 
Die Karten passen leicht hinein, sowohl hochkant als auch quer. 
Um die Karten zu schonen und für eine bessere Haptik, sind alle Kanten abgerundet. 
Mit 49g PLA ist er relativ materialsparend und dennoch stabil.

Edit Feb 06, 2025:
I deleted the A1 mini print profile today, based on the 1 star rating and the comment from user_687708798 on Feb 06, 2025. 
I had tested the print profile extensively before uploading it, it had already been downloaded 80 times and had a 5 star rating until today. 
Nevertheless, I take this comment seriously, and must assume that there is a problem here (which unfortunately I am not yet aware of).
I will only put the print profile back online when the alleged problem has been solved.