Any ideas from the engineering community - "How do you make a spring - 'spring' ???"

[gravity sucks]

Thanx guys...

[Scooby]

The chances are the biro spring won't have a high enough Carbon content to harden properly.

If you heat it until bright Orange/Red & drop it into some water this will quench the spring but it will be very brittle & is likely to break when compressed. You now need to temper the spring which will slightly soften it but make it much tougher so it won't break, this could be done in the oven but you can lightly play a lighter flame over the spring a few times without it turning red, let the spring cool in air & it shouldn't break. If you want to do it in the oven, stick it to it's max & leave the spring in for 30mins - 1hr before removing & air cooling.