Do they have free packing supplys at the post office?

[yourharddrive]

I gotta ship something and i cant find a box that is the right size...

 

[bunker]

They have supplies, but they're not free.

 

[glen]

They have packing supplies for sale.

 

[ShotgunSteven]

The boxes are free.

 

[morkinva]

the boxes are free for priority mail and express mail service only.

 

[EagleKeeper]

Boxes for non Express/Priority will run you between $1-5.
Plus you will need packing material, which the PO does not carry.

For your effort/time, think about one of those MailBoxes type places that have the packing and boxes available.