As the title says! I've been using the smallest pots in the IKEA PRUTA range for DCs' packed lunches, but they leak if I put things like hummus/other dips or yoghurt in them. Need to replace them with something totally leak-proof for more liquid food and was going to opt for Sistema snack pots, but then I thought this might be a good time to get something more eco - maybe stainless steel? Bamboo (though would much prefer things I can stick in the dishwasher)? Don't think glass would be a great idea with young DC... They need to be small, say between 60-200ml. Any tried and tested suggestions?