hello - new to arduino and looking forward to the tinkering/learning. in the starter kit i purchased, it lists 'things you need to supply' which includes a 9v device that includes a switch/pushbutton that i'll be hacking. i'm having trouble thinking of anything... the only thing i have lying around are those little flashlight caps that you snap on to a 9v battery. they have a switch, but i don't know if that would be good enough? i don't know if i need to prefer something that has a case that can be opened (i.e., screws, or snapped together).