Most box holders on the market are for the US Nintendo DS boxes, those are thinner. This US holder I remixed is for the European Nintendo DS boxes. The cartridge can be placed in front of the box. No logos, just a simple holder to show off the game.

No support needed, print with 10/15% infill. If you want the top to be smoother, print with 0.1mm detail instead of 0.2mm.