You need to obtain 3 parts out of the ISA card support: the dit and dah contact brackets and the lever bracket.
The lever bracket must be made out of a 2.5" long piece from the ISA bracket.. If you have an ISA card with the mouting screws, cut the 2.5" piece between the mounting screws so that there is about the same amount of metal left with each screw. Bend the 2.5" piece in the middle so that it holds the piece of saw blade, then bend the end pieces about 1/2" from the end to make the mounting feet.
Drill mounting holes in the feet, then glue the blade into the lever holder and let cure. Make sure to put the teeth of the blade facing down.
Use the parts left over from the ISA card support bracket to make two right angle brackets about 1/2" high and 5/8" long.
Drill a 1/8" hole in each for mounting the contacts to the wood base.
If you had an ISA support bracket with the screws, these screws are just right for contacts. Otherwise, you just have to drill more holes for #4 screws for the contacts. In either case, you may want to gently file the tip of the screws to round them. This reduces the risk of damage to the contact during heavy use.
The glue holding the lever to the bracket should be cured before assembling the handle. The handle is made by cutting the wood dowel in the middle along the length. Then glue both halves on the end of the saw blade and put the shrink tubing over. Alternately, you can use electrical tape to hold the pieces together while the glue cures.
I prefer my paddles to be heavy so that their own weight (helped by the non-skid feet) holds them in place on the desk. The only problem is to find enough lead in the proper size for that purpose. The weights used in this project come from a worn-out pool brush. The lead helped the brush stay at the bottom.
First, install the copper tape on the lever so that it covers the area where the lever will touch the contacts.
Then mount the lever support on the base using 2 screws.
Then mount the contacts, leaving a small gap (I like the gap really small to make the paddle sensitive, but your preference may be different). You do not need to spend too much time locating the contacts precisely, since you will have to fine tune the adjustment after assembly anyway. This can be done by bending the contacts with pliers.
Finally, solder the wires from the headset. If Murphy is on duty, you will probably have the paddle reversed initially, no matter how much time you spend to get it right, so do not worry about it, solder the wires and check it. If it's reversed, swap the wires. I also solder a wire from the cable's ground returns to the copper tape. This way, the return does not depend on contact between the copper tape and the blade, and between the blade and the bracket.
At that point, you can take the paddle apart one last time to paint the base.
7) Final Assembly and check-out:
After the paint dries, reassemble and readjust everything. Then you are ready for your first contact with the KO4BB Single Lever CW Paddle.