You can do everything right

 With tumblers I've tried different methods to make awesome cups.  For the most part they turn out awesome and look good and there's no problems.  Every so often there are problems.  

 This cup I originally hadn't put epoxy on it as it was my first attempt at tumblers.  My sister used it 3 months and the letters started coming off.  She asked if I could fix it.  I got it back and ended up removing all the lettering and starting over.  I then put epoxy over it to help make it last longer.  It turned out awesome but there were some problems getting it done beside the fast turn around.  The tumbler fell off the turner and the epoxy pooled at the bottom.  Put it right back on the turner and hoped for the best.  I had to do a second coat to finish it up but it turned out awesome without having to start all over.

Then there is this one.  My cousin requested a tumbler.  Put it on and had no issues with the turning process but this happened.

There is a lovely wave of the epoxy on the bottom.  No reason at all and unfortunately this isn't something that can be fixed so I have to remove all the work and start over.  I love the effect of the glitter and alcohol on the cup.  It looks amazing but it can't be fixed.  It is the biggest issue with epoxy as I did everything correctly but it still turned out wrong.  The next one will be better!