So the general idea is this: I am in the process of working out a contraption that can extend and retract a blade in and out of its sheath. It is very similar to a switchblade knive, but on a larger scale. I have come up with a design (which for patent and invention reasons I won't mention), however this proves to be quite a meticulous process. I project the final project to have 1 to 1 1/2 foot blades protruding from their sheaths, and while I can manage on having them extend (but any ideas to better the product are appreciated), I am in need of a way to, with equal force, have the blade return to its sheath. I do not know if I've made myself clear as to what it is that I am trying to achieve. If you have any questions concerning this, I would be more than happy to help in any way I can. That you to all who help make this possible.