I used to make these with spare chunks of 2x4 wood for my handicapped brother. But, now that I have a 3D printer, I can just print a new one any time he needs one.

He really liked the 2x4 design - better than another 3D model I downloaded and printed. So, I duplicated all of the dimensions of the 2x4 card holder. 2x4 (1.5"x3.5") x 7", with five 10º angled 1/8 inch slots. You can hold an entire deck of cards on this.

Update: I just printed 6 of these for the whole family to play cards. So, I had to refine the best way to print, using the least filament, while printing fast and strong. This is what I came up with:

1. Use a 0.8 nozzle.
2. Print with 0.6 layer.
3. Set outer shells to 1.
4. Set top and bot layers to 2.
5. Set infill to 10%

This takes 2hr 44min to print and uses about 230g (1/2 pound) of filament.

Ultimaker

Ultimaker 2

No

No

0.8 noz, 0.6 layer

10%

With a 0.4 nozzle and 0.3 layer height and 10% infill, it takes 12 hours to print.
I'll upload both a horizontal version and a vertical version, but I suggest the vertical version so the layers strengthen the weak points where the slots cut deepest. Printed on it's side vertical makes the layers perpendicular to the weak zones and should keep it from breaking too easily.

Update: Best way to print, using the least filament, while printing fast and strong.

1. Use a 0.8 nozzle.
2. Print with 0.6 layer.
3. Set outer shells to 1.
4. Set top and bot layers to 2.
5. Set infill to 10%

This takes 2hr 44min to print and uses about 230g (1/2 pound) of filament.