Go to a gun shop
a screw, a lever, a wedge, and a wheel and axel. The wedge is found on the cutter, the lever is the handle, and the screw is the device that holds the canopener together.
When Davis arms went out of business Cobra Pistols bought their equipment and continued to make Derringers under their name. I believe all the parts are interchangeable, See link below for Cobra pistols.
Scissors are typically classified as a type of double lever, where the two blades act as the lever arms with the pivot point being the screw that holds them together.
Not sure which spring you mean, or what you mean by "case"? If you mean the receiver, then you might be referring to the cartridge cutoff spring, or the lever spring? The lever spring is held by a screw just in front of the lever pivot screw, and keeps pressure on the lever, so it wont droop. The cartridge cutoff spring installs in the top of the receiver, with a screw through the top that holds it just behind the chamber. These are my best guesses, since i don't have good info.
A screw holds better than a nail.
Screw
A vise has 2 simple machines, a screw and a lever, but the main one is the screw.
ldk
Gun shops, gun shows, want ads, internet searches
A screw driver is a class 3 lever, where the effort is between the fulcrum (the place where the screwdriver pivots) and the load (the resistance of the screw being turned).
First Class
Its a simple machine