The two blocks and various parts of the original Evergreen Hand
It has gone through many revisions since.

The wooden block is formed by two identical pieces which clamp the lower end of an “S” shaped connecting arm that fits into a slot, seen in the above photo.

The S-arm fits into the slot, and positions the metal plate.

A metal plate is clamped to the upper end of the arm. The metal plate serves as a mounting platform for several tools that attach to the plate by magnets.

The tools have magnetic bases, which allows them to be easily adjusted, yet they stay put.

The clamping friction is adjustable at both ends so that the arm can be moved in an arc while the metal plate can be rotated around the metal arm.

The arc of movement would be similar to the tier's upper arm and forearm motion, while the rotation of the plate would be similar to the tier's wrist and hand action. The tools function as fingers. Grasping and holding of material can done with any one of several tools and an additional tool is used for thread control. The only limitation on the type of tools you have is your imagination! The type of tying material would dictate whether the small alligator clip on the wooden dowel or the test lead clip on the cork are used. Both have magnets attached at the base which allow them to be moved like fingers around the metal base. This “arm”, “wrist”, “finger” combination allows for motion with a full 6 degrees of freedom, including the rotation of the tool being used.

The third tool requires a little more explanation. This tool is used to make the soft turn used to tie the tail on a fly. It has a small metal finger (SMF) that can be locked in a horizontal position or unlocked and allowed to rotate down to a vertical position. The tying thread is brought from the near side of the hook shank up and over the horizontal SMF and down the far side of the hook. (See this video for more information.) This forms a loop above the hook shank which allows the tier to position the tail material inside the loop and on top of the hook. Next the thread, material, and hook shank are pinched with two fingers while a third finger unlocks the SMF. The SMF rotates downward releasing the thread loop and allowing it to tighten around the pinched tail material. Several additional features are incorporated into the wooden block base. The round dowels on top of the block rotate against each other, cam like; this grasps and holds one end of the material. The small metal eye is used when working with marabou. Insert the feather in the eye, butt first, and pull down. The result is a gathered plume whose length can be adjusted with one hand. There is also a cork disc on the end of the dowel. This allows the tier to stick a hook in the cork and grasp it with of the clip tools. The tool is then positioned on the metal plate to hold the hook while the vise jaws are closed around it.