In a Vera zip ID case attached to the key tether in my Disney Dooney small letter carrier.
With MaxPass obviously that'll have to change! I hate the idea of having to take my phone in and out multiple times for scanning as it increases the chances of dropping or damaging it. It's one of the reasons I wish DL would start using MagicBands. They were so convenient at WDW and DL could use them with the new MP system as is, MBs do not have to equal FP+.