Another tip I can give is to try & crack the nut with the car still on the ground, less chance of the damper rod spinning with the weight of the car on it! Use the same method to tighten it to the correct torque.
Usually come off fine IF I remember to do this before raising car or removing anything else.
Crude way I made same tool, take correct sized impact socket, grind down a little if too thick, grind two flat sides on to of socket, used spanner on flats with hex key down the middle, tool can be created in small amount of time ith just firing up bench grinder.
Long ago I took apart the whole thing, then needed to attack the junk strut bearing the very hard way with saw, chisel action to reuse the struts, super D'oh!!