Sometimes it's the most simple things that make the most heartfelt sounds. There has always been glass bottles around just waiting for air, and of course the harmonica is a pocket worthy instrument. I've come to find I'd miss my acoustic guitar, but wouldn't be up for carrying it.. maybe a banjo or ukelele would have to suffice. Congo drums, bongos, and really any African/ Jamaican/ South American/ etc. drum could be found in a "travel size." With all this said, there is an instrument every one of us carry around and it is the voice. Singing, music in general is what could bring the world together. When those of us are lonely- we only need the company of voice to fill the hole. So here we all are carrying a weightless instrument.. Let it be as free as you are