If there is something to grab onto(and I’ve had to pull a good many miracles using this method):
A pair of pliers, some patience and a decent method to secure the object can go a long way. There was an earthquake and a 60-inch rack full of gear, well, the heads of all bolts sheered(as by design), but then all this high-end gear came crashing down. Fortunately, the damage was minor. I had to remove each bolt by hand using this method. I didn’t need to secure anything, the rack was heavy enough as it is so it wouldn’t go anywhere. I had at least .125" to work with on each bolt. I’ve had to do it with less bolt sticking out to work with, but not in the same numbers. For me, 1-2MM is plenty to work with if you are willing to be patient and have a really good set of pliers.
This might be a good time to suggest that it might be advisable to stock up on replacement parts. Now that you bring up this example, when I buy some stuff here in the next few weeks, I think I’ll add some replacement axles to the order just to cover accidents. They are so affordable you could buy them a few at a time to have available for emergencies, or for routine replacement. Plus, if you didn’t buy from here, contact the sales folks for advisement on what you should purchase. They’ll make sure you get set up properly. If they put up with my questions, they’ll gladly answer yours as well.
I haven’t tried those bold extractors. I’ve been fortunate to have something to grab onto. A brother in law had to get some bolts out of a snow board that sheered at the deck level. He used a bolt extractor set. It worked for him.