if you feel that the time is right to progress from a sippy cup, don't fancy plastic beakers and you don't want to take a chance with glass, why not try an enamelware cup? (and if your kid needs any sort of convincing you can tell them it's what cowboys use!)
falcon enamelware cup tumbler howkapow red white blue alternative to plastic metal bpa free babystylefile baby style file
1/ white and blue enamelware tumbler, £5.95, howkapow
2/ red enamelware tumbler, £5.95, howkapow