Pro Mini Enhancement (3.3V/5V adjustable)/16MHz MEGA168 (Arduino-compatible) US $9.30
To program it : -
FTDI Basic 6 PIN 3.3/5V For Arduino(Free USB Cable), US $6.90
Triple Axis Accelerometer ADXL345
HMC5883 Module Three-Axis Digital Compass
A3144 A3144E OH3144E Hall Effect Sensor, two of.
5mm RGB LED Diffused Arduino (Red Green Blue in one LED) Shared Cathode, two of.
Resistors :- Four 220 Ohms, two 8.8k and two 11K Ohms.
Test bed was :-
ARDUINO UNO Proto Shield + Breadboard
And for further testing ... you really need a larger breadboard ... its so much easier..
830 Points Tie-points Solderless Breadboard Circuit Bread Board
The Test waterproof container is like my dive lights but specifically:-
21mm solid Rubber Stopper (rubber bung) for each end.
25mm x 2mm CLEAR Acrylic Perspex Plastic TUBE Pipe 1M.