I am not much of a straight key user, but I am building one anyway to be a park of my novice station. The hinge is brass, the arm brass, the knob is a a button i found in the wifes sewing collection and the spring is one i picked up from the hardware store and the base is red gum.
A little progress, using the cnc, routed down the board, retaining a plinth at the rear to mount the arm to. Need to drill out a recess to house the spring, and also another for the contacts at the front. I have some Copper rivets on the way to use as the contacts and some longer brass bolts for other side of the contact, with tapping the bar and a lock nut, the contact gap will be adjustable.