random target mover

i want to make a shooting target controller, i have an ardunio uno and i want it to operate 3-5 motors/servos, turn the target 90 degrees at random times. but i want to be able to have different time intervals like (10 sec, 15 sec, 20sec, 30sec - if its possible). would i need a motor controller? and how hard would this project be?

If you're only using R/C servos, you don't need a shield, and even if you do need a shield to operate motors, it's all very simple.

but i have no clue how to right the code for that i did right this but how can i modify this to do what i want to do

#include <Servo.h> //include the servo libary

Servo myservo;  // create servo object to control a servo
// a maximum of eight servo objects can be created

int pos = 0;    // variable to store the servo position

void setup()
{
myservo.attach(9);  // attaches the servo on pin 9 to the servo object
}

void loop()
{
for(pos = 15; pos < 90; pos += 90)  // interverls
{                                  
myservo.write(pos);              // tell servo to go to position in variable ‘pos’
delay(180000);                       // waits 3 minutes for the servo to reach the position
}
for(pos = 90; pos>=15; pos-=90)     // max rotation
{
myservo.write(pos);              // tell servo to go to position in variable ‘pos’
delay(250);                       // waits 1 second for the servo to reach the position
}
}

Moderator edit: CODE TAGS.