I modified the OpenScad code for the  customizable card game box in order to have the cap and box line up flat. 

Printed this front plate i created in HueForge. 

I used prusaslicer to cut the plate where the cap and box meet. You might also need to scale the model in X and Y direction to fit the box you want to attach it to

For printing the plate you need to use the following settings:
Print at 100% infill with a layer height of 0.08mm with a base layer of 0.16mm

You need the following filament swaps:

1. Start with Red
2. At layer #9 (0.8mm) swap to Orange
3. At layer #14 (1.2mm) swap to Yellow
4. At layer #20 (1.68mm) swap to White for the rest.