Something I've always wanted since I moved to Japan three months after the Fukushima Daiichi nuclear incident was a portable Geiger counter. I've been interested in radiation since I was a child, but never did anything about it until then. At the time, I danced around the idea of buying a b-Geigie Nano kit by Safecast; roughly $300 unassembled. However, I didn't have the fiscal liberties as I do now and never bought it.
Skip forward seven years later to March 2018 and I return to see the price has jumped to $600. Given I could buy competed and certified Geiger counters on Amazon for much less, I decided to look around for other assembly kits. That's when I found John's site DIYGeiger. For roughly $75 I had everything I needed to build the GK-Plus kit; minus the battery management, GPS, and housing. It provided all the features the b-Geige Nano kit offered and more.
The assembly took about a whole evening to do, and another evening to clean up and test. The video below is my first test run using uranium cracked glass marbles.
After my initial test I moved on to designing the custom acrylic housing and custom controller board. This was the most time consuming part of the project. I had to make all the parts fit into a pelican 1050 case with enough room left over to fit the remote. Using a caliper I took precise measurements of all the components and translated them into a vector file under the illustration program Inkscape. This vector file was then handed over to Ponoko.com to laser cut the acrylic housing parts. My first design was successful and I had my Geiger counter completed by May 2018.
I used the kit like this for the rest of the year, visiting antique shops and collecting interesting items over the summer weekends. A year later I refined my design, improving the wiring, shielding, and slimming the acrylic housing. After I was done I celebrated by having it officially certified by the Nuclear Regulatory Committee.
All said and done, my Geiger counter is significantly better than the b-Geige Nano in every aspect; speed, memory, controls, battery life, sensitivity, etc. The only con is it's slightly larger, but I can live with that.