DC power delay?

Hi there. I am working on a project that requires a delay for the power. Specifically, instant on - delay off, after switch is released. Three things stand in my way:

1. I have NO electronics knowledge.....at all, well, I can connect a switch to a battery to a motor.

2. After the required 10-20 sec. on delay, it must turn off, but be ready to be switched on again at any time, ie. momentary switch.

3. Must be relatively low in cost, and easily reproduced, 100-1000s of times for a possible commercial product.

I am prototyping an item that is fairly simple in design. Push a button, relay trips, motor runs for 10-20sec, then shuts off. Push it again, it all repeats. Power is supplied by a battery, most likely 7.2 NimH motor is 6-12v.

Any help is greatly appreciated!

Try this .....you may need to change yr timing cap if you want more or less delay-the delay time is dependant on the setting of yr 1m variable resistor....

I don't think he wants a trigger, just a simple, power on, stay on for 20s, then turn off.

Here's an idea.
R =150k
C = 100µF

Hero, thats exactly what I am looking for. But, is there a resource for what it is exactly I am looking at in your diagram? I did some searching, but am coming up short on symbol explanations. I am good at the whole assembling part, just need to know what I am looking at first. Thank you very much for that.

http://www.kpsec.freeuk.com/symbol.htm
http://www.kpsec.freeuk.com/555timer.htm
https://www.electro-tech-online.com/custompdfs/2009/08/LM555.pdf