If you find AMSAT interesting, you'll probably also enjoy the high altitude ballooning (HAB) projects. This guy [0] built an 11-gram transponder payload and floated it up on what was, essentially, a mylar party balloon. It circled the globe at least once and came ashore over the northwestern U.S. near Tacoma, WA and I was lucky enough to pick it up on a handheld radio while standing in my backyard [1].
[0] https://amsat-uk.org/2014/07/31/434-mhz-balloon-b-64-complet...