Belt Buckle - Roller Coaster Style

Belt buckle in the roller coaster style, fitted for a 1.5in~37.5mm wide belt.

It's fully 3D printable so you can scale it to other sizes, but I don't recommend going smaller considering there are small parts that aren't a walk in the park for every 3D printer to make. I found printing the spring at 100% infill feels the best, but 15% infill also works.
 

If you think the plastic springs are too awkward here's a version that uses metal springs:

https://makerworld.com/en/models/1770679-belt-buckle-roller-coaster-style#profileId-1885041 

This version is “Belt Buckle-A001.” 

Build instructions are included in a pdf file.

Printing Estimates/Stats:
15% Infill - 22.25g - $0.45 cost(PLA) - 1h0m printing time
 
*Note: there are alternative options for: buckle 3 and buckle 5

*I'm noticing after about a 100+ cycles of actuating the spring in a short period of time the latch weakens. I'm looking into strengthening the latch mechanism and will update if there are improvements. I don't take responsibility for any wardrobe malfunctions, use at your own risk. 

*Update(5/14/24): Improved the latch mech a bit, should be a bit stronger now. Also added a new slightly thicker spring.

*Update(5/13/25): Added alternatives for “Buckle 2” and “Buckle 2-2” to give the double holes that match the other side so you don't have to sew the belt.

Parts Lists  for printing:

(x1) - Buckle 1 [*requires support]

(x1) - Buckle 2 [*requires support]

(x1) - Buckle 2-2 [*requires support]

(x2) - Buckle 3

(x2) - Buckle 4 [*consider higher infill + brim]

(x3) - Buckle 5 [*consider using brim]

(x3) - Buckle eClip [*consider using brim]