I made my daughter this robot costume for halloween. I was inspired by this Kid Robot costume. I took mine in a bit of a different direction and added a few more novelties such as lights in antennae and ears, a big button pad with a sound effect for each sound, and my daughter’s actual voice for the candy detector and a few other phrases. I also added pressure sensors to her boots so that she had robotic sounding steps.
Adding quality audio to an electronic project is surprisingly difficult. Here is a shield for Arduinos that solves this problem. It can play up to 22KHz, 12bit uncompressed audio files of any length. It’s low cost, available as an easy-to-make kit. It has an onboard DAC, filter and op-amp for high quality output. Audio files are read off of an SD/MMC card, which are available at nearly any store. Volume can be controlled with the onboard thumbwheel potentiometer.