Over on their YouTube channel there have been numerous talks uploaded over the past few months from the 2023 Society of Amateur Radio Astronomers (SARA) conference. Some of these talks are quite useful for beginner radio astronomers who are getting started with small dishes and software defined radios like the RTL-SDR.
One talk by Alex Pettit describes how to build a radio telescope from a an umbrella and some "Faraday fabric" which is copper cloth. The results show more than adequate performance for the cost, making this an affordable and easy entry to radio astronomy.
Another video presented by Dr. Wolfgang describes building small to medium sized radio telescopes. He explains how small radio telescopes less than 3 meters in size can work well for receiving the 21cm Hydrogen line, and how SDRs are the best choice of receiver for them. Many examples of small dish installations are shown.