Hello, here is a buckle made for a stretcheable belt. I used a 38mm wide elastic you may recognize it :D
**Warning Buckle part is 44mm wide it won't pass through jeans loops but the part called belt end will its only 38mm wide. So if you print it for weareable belt, print both parts
Belt_end_38mm_wide.STL | 71.7KB | |
Buckle_44mm_wide.STL | 40.3KB |