Hey I'm not sure where to share this but... Did you know you can mail letters and postcards up to a certain weight and size for only 2 cents? It works, Ive done it. Try it yourself if you doubt it. You have to address things a certain way but I just thought I'd share if people wanted to save on postage for simple letters or postcards. Here is a video explaining why and how to do it. It's not a scam or trick. Again, I've done it multiple times. Like a lot of things if you ask the postal service they will tell you otherwise but they may be ignorant or just trying to make more money like any other corporation.
I encourage you to look into the laws surrounding the post office. It was covered a bit in the above video. Basically, the way I understand it, a corporation swallowed this service up and is now charging anything it wants. However they do so with the post office still within their system. Therefor the laws regarding sending simple letters and postcards still applies. I think the confusion may be the multiple layers of corporate or legal rulings and the original law and the mixing of the two.
Rocket Mass Heater Plans: Annex 6" L-shaped Bench by Ernie and Erica