They look good and after assembling the parts, the design works, well I've not tested the 868MHz transceiver yet but the LCD display connected to the Arduino Mini Pro clone works fine and when connected to the sensor fitted to the gun all seems to be OK.
I used a scope to check the calibration of the value sent from the Arduino and it looks pretty good.
|Front View - LCD and switches|
|Back View - the Mini Pro plugged in|
|Various part plugged in|
|Scope display showing time between pulses|