Is the telescope design available anywhere for hobbyists to build? I can't seem to find anything in the article or in a separate search. I'd be interested in perhaps putting one of these together to do radio astronomy with my kids.

Maybe you like this:

https://physicsopenlab.org/2020/10/10/a-simple-11-2-ghz-radi...

The HN discussion (2020) about this can be found there:

https://news.ycombinator.com/item?id=26078761

Search on “diy radio telescope”, that gave me lots of projects and videos