Taylor Swift Concert Cup Lid

I was requested by my niece to design a lid for her cup.  

I made over 10 prototypes to get the seal just right.  Although the one shared here is a little lose to make it easier to put on and take off.  

Adjusting the seal 0.10 mm could get a tighter fit.  In test.  The tighter specification made it hermetical.  

The tests were printed using PETG