This is part of my modular belt buckle project. The buckle is made of two parts; one is a frame base, and the other is the insert that simply press-fits inside. I separated them so that you can pop inserts in and out easily (especially with the new punch-out hole on the base), and also to enable color-swapping when printing the insert for multi-color prints.
The only piece you'll need that isn't 3D printed is the metal buckle itself, which just needs to be glued to the back. I wouldn't trust this piece 3D printed, so I recommend this one: https://www.amazon.com/Best-Belt-Buckle-Blank-Rectangle/dp/B07L5TN6F2/ref=sr_1_2?keywords=Creativeglasswork&qid=1560366222&s=gateway&sr=8-2
This large batch of stuff is the Marvel collection (which is likely growing). If you have an idea for another collection or one-off, let me know.
EDIT 6/14/19: Added Captain America insert.
EDIT 6/19/19: Added second (much better) Captain Marvel insert (this is cover photo)
NEW! Marvel Collection 2: https://www.thingiverse.com/thing:3696421
I've designed the logo with multiple heights to enable multi-color prints without a multi-material machine. You should be able to pause the print and swap colors easily enough, especially if your printer firmware supports the M600 GCODE command (filament swap).
I used Prusa Slicer to slice and enable those color changes. I did have to set the top layers and outer perimeters to 0.3mm in order to get the fine detail to print properly.