HI,
3 nights 2 full days?There are a lot of places worth visiting.Such as Mount Emei,Leshan Giant Buddha,Dujiangyan water conservancy project, Qingcheng mountain,Sanxingdui Museum,Huanglongxi ancient town.
I suggest you this itinerary.
itinerary
Day1,you fly to chengdu.overnight in chengdu.
Day2,You become the panda volunteer.afternoon 16:00,go to Emeishan,overnight in emeishan.
Day3,go to golden dome,Watch the clouds sea and temple Temple.afternoon visit to Leshan Giant Buddha,and then back to chengdu.
Of course, you can also visit mount Qingcheng and Dujiangyan water conservancy project.