One aspect of the Summer Wizarding Event is a Post Office. We are still working out how it fits into the narrative of the day, but the idea of our new students receiving mail and being able to send some has got us pretty jazzed.
I am big into letter writing myself (what a surprise!), and have a very neat cabinet given to me by my Beloved Spousal unit that is designed for storing one's stationery, stamps, labels, and such. Recently on a run to Goodwill I came across a similar-looking cabinet.
I've modified it by painting the logo of our Postal Service on its doors and antiquing its entire inner and outer surfaces it with "Ancient Gold" "Rub-n-Buff Metallic Finish." The postage stamps in the image below are real (old) U.S. stamps in 3-cent denomination. Professor Science donated them. Besides being used as postage for the fictional mail the kids will be receiving, there are enough stamps for each kid to receive their own small stamp set as part of an informational brochure they'll be getting (and I will be authoring) on How To Create A Fictional Correspondence.
The postal scale is something I found on eBay. It's a bisque-colored plastic. I haven't decided yet if I am going to paint it or leave it as is (I actually use it, so I'd want to be careful about using something that might damage the surface.)