You can create your design in any graphics edit program that allows you to export vector paths in the SVG format. If your design contains any text, be sure to modify the typography so that the counters have gaps. You can check out our tutorial on optimizing typography for 3D Printing. Once you have your artwork, import the .svg file into Tinkercad.
With your artwork imported into Tinkercad, scale the size of the object if it's not too big or small by using the scale handles and holding down the shift key to constrain the proportions.
Now we need to align the two pieces together. Select your design and buckle cover and click "Adjust > Align". To do this in Tinkercad, click on each middle points to align each side. Now, select the design and turn it into a hole by changing the color type to "Hole". Now combine the two objects together by selecting both objects with the shift key and select "Group".
Save and export your design as an STL.
Save out the .stl and now we're now ready to print!