I’ve had bad luck with little red cups. I had one that I made last year that I gave away to a friend, so I wanted to make a new one to replace it. I made one the first day, and it looked pretty good, but it fell off the punti because I pushed too hard with the jacks. Then I made a second one that survived annealing, only to get broken while removing the bit of punti that remained. this is the third one and I think it turned out okay.
It does strike me as ironic that I still can’t make cups as good as the cheap Mexican ones you find in Tucson or at Macayos.