A police light was needed, urgent indeed and to be mounted on a true police bike. So I went down to the electronics store to get some pieces.
A call to the engineering hotline revealed I would need 8 regular batteries to power the 12V - 120mA flashing light. Assembly with drilling and soldering took place on a quiet and comfortable Saturday evening.
The final result was quite satisfactory. I left out the siren intentionally to spare his parents' nerves.
"This looks good" my little cousin said. He was happy.