Here's a practical tip from the road if you use a wine glass for your show. If you do, chances are you've opened your case at some point to find it broken. Never again, I say! I found these travelling wine glasses in a camping store.
They are 100% plastic, though they look like high quality glass. Made for the rugged life of camping and backpacking, these aren't going to break easily. Better yet, they unscrew in the middle, and snap into themselves for storage.
The larger size, made for red wine (as you'd be the laughing stock of the campsite if you tried drinking red wine from a white wine glass!) also perfectly fits a poker size deck of cards. In storage mode, I suspect it might be the perfect spot to safely keep a small egg, stuffed in with some paper tissue, if you're using it for a silk to egg routine.
In Canada, they are $7.95 at Mountain Equipment Co-op. You can also order them online direct from the maker GSI Outdoors