It's an espresso cup! Made to hold 80ml to the brim, it's the perfect size for an espresso doppio. If you choose to print with PLA (HTPLA) and then heat-treat the part, it may shrink slightly (the slightly oversized cup allows for some shrinkage). Here's my design and heat-treating process: https://www.youtube.com/watch?v=WNvXFYG-C2s