DS has been known to pinch people's keys and when I've found them in his pockets I've had to go return them,we did end up with numerous bunches that apparently nobody was missing any. His new obsession is people's ID badges that teachers ect wear,however if you've had an haircut since you got the photo the boy ain't happy
Definitely the portion of the obsession where he is invading peoples' personal space must be discouraged for safety, but there is a fine balance (and a tough one to find).
DS went through a watch phase and a key one... For the watch one, we got him a couple of watches from a jumble sale - one analog and one digital, and then I found a stopwatch, too. That helped him confine it to something in his own hands, particularly when we were out of the house. I did the same thing with keys, he got his own keyring. I dug through the drawers at home to find the inevitable "fits nothing" keys and put them on a ring for him - which I attached to a chain and hook so we could clip it to his belt loop. We went out to the shops and I let him choose 2 key blanks and a fob for his ring (i just bought the keys uncut) and he was a happy boy.
Not as sure about lightbulbs - might he be happy to have a small LED torch he can carry? Perhaps looking at lightbulbs on the iPad can be a reward for a good trip out to the shops (maybe where he didn't touch anyone).
He always seems to get obsessions about odd things,at the moment it is lightbulbs.he wants to look at pictures of lightbulbs on the I-pad all the time,I'm thinking of limiting his use of the i-pad as I feel he is isnt learning or benefiting from doing this. He also loves watches and clocks and he will go up to complete strangers when we are out and want to look at their watch,same with car keys which he also loves,he will try and go into people's pockets to get their car keys.
I always explain to him that he can't go into other people's pockets but I don't think he understands and he just carries on doing it.
I'm not sure if I should be trying to discourage these obsessions or not?