Smaller models are a little more tricky to print in a good quality. Consider reducing the print speed. For precisely connecting parts you may need to adjust (not necessarily):
Recent HotWheels compatible printable model addition
Hot Wheels ramp with HotWheels tracks adaptor.
I've also created more models that you can be stacked horizontally as well as vertically.
Below is a preview of the display shelf you can achieve with my other display modules. You can see & download them here.
The author marked this model as their own original creation.