1.5 V would be the voltage from the battery running the [small] motor, not the trigger signal
what kind of current/ voltage can this thing handleor need(does it need 9v)?
A simple method is to take a 5VDC relay (the coil voltage is 5VDC) and use a 9V battery say to activate it. Of course you will a series resistor with it to limit the current and dont destroy it. If you connect a capacitor in parallel with the relay coil you will get a delay and then the relay will be activated. In simple words, the delay will depend upon the capacitors value, the larger the capacitor the greater the delay.
Yes you can but the time wont be actually RC, its depends on the relays pull-in voltage and the resistance of the relay coil. You can use another relay with a capacitor in series with it as to stop the motor after 3 secs.
I'm working on a circuit design, but in the mean time....
How durable are relays and capacitors? motors? can they be dropped, thrown ?
can they be thrown consistently in a padded environment?
does engulfing everything in glue help??