Solarpunk technology

If you want to build this specific DIY device (as it's quite cheap), then it's probably worth clicking around the video to find the relevant bits of assembly (as a good portion of the video is just demonstrating its range and weatherproofing). If you want to avoid Google seeing you watch it, I believe Freetube still works to circumvent that.

There are some written guides for building a similar device but...

• This guide and this other guide don't appear to mention how much they cost to build without looking at each part's product page.
• This guide does mention the price of the build, but it's quite expensive at $120 per unit.

Alternatively, there does exist this pre-built solar meshtastic node, which is $79.