I've made the clampy thingys out of old aluminum VW pushrods.
Cut the rod about 1 inch long. Drill a hole through the rod right in the middle - the same size as the heater cable end.
Take a 6mm tap and run it through the end of the push rod well into the area of the hole you just drilled. Use any 6mm
bolt (10mm head) lying around (can even use the engine tin screws in a pinch).
Viola - that's it!
Works for stock carb throttle cable clamp as well.
Now if only you had some old pushrods lying around.......