Made a geiger counter from a kit. It's a MyGeiger kit from RH Electronics.
Its very good!
Inside
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Rear of pcb, with LiPo 1100mAh battery, charger and serial to USB converter 'mods' allowing charging from USB and datalogging via USB.
SV203909.jpg
In the case
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Almost completed unit
SV203911.jpg
Work to do: Add external detector socket and switch, make alpha pancake detector probe and beta/gamma detector probe.