Agility and reaction timer for sport

Looking for someone who can make a agility/reaction timer or make the plans for it so it can get to work.
Found on YT (https://www.youtube.com/watch?v=820YiXvPF9I (after minute 10')
Great for sports like badminton.
One controler that choose the direction left/right and times the reaction-time.
Timing is optional for me....
Found it also in Japan on internet www.onigoe.net
But making one with flashing light with adjustable timing. Random left/right.
Anyone?

Doable, but not free

1+
Should not be too hatd to get this into a small microcontroller like an Arduino.
Back when I was in school our teacher even had a manual stop watch that stored 3 different lap times and the complete time - mechanical...

*maniacal...