The card holders can be put together with magnets.
4x 8mm x 2mm
https://www.ebay.de/itm/115045609445?itmmeta=01HQV241NA6D64YFVSQP5RTD64&hash=item1ac940afe5:g:OcMAAOSwB9ZhZ~ds
If you are interested in creating a remix, please contact me for the raw file.