This model is a simplistic, functional design with an accentuated back and clean, powerful angles. Clearances for the business cards are tight on purpose so that the cards do not slip around too much.
I highly suggest just using the .3mf files or printing the main model at a 45° angle (.stl is pre-configured this way) using supports. The model was created with this in mind - it gets rid of the top surface looking different from the front slope. The back overhangs would also be difficult to print without the angle.
If using the .stl or .step, make sure that you also print the model sideways on a bedslinger - the supports might otherwise come loose and the print in turn fail. And use 2mm clearance for the supports for a nicer surface - they are only there to hold the model, not to support excessive overhangs.
Filaments used: Prusament Marble Grey and Azure Blue
Cheers!
The author marked this model as their own original creation.