Ahhhh
There's no real reason for this post other than I am on my own with DS and DD this weekend, and DS's current 'thing' is making 'trails' (so basically lining up in an intricate fashion), sometimes playing cards, today dominoes (and we have about 300) they are currently all over the kitchen and dining room floor making it impossible for me to walk anywhere without knocking them over and then of course he freaks out.
I've suggested we make a video so he can preserve the memory forever, which he seems happy with - but every time I go to do it he says he's not finished yet 
Currently he's shouting at DD for running his trail when she accidentally trod on one trying to get to the loo.
He won't play in his room at the moment either as he's scared of being on his own.
Ah well! No need for suggestions really - just needs to write it all down somewhere!
He doesn't tend too obsess over a subject (like you hear about trains or dinosaurs) but becomes fixated on doing one thing endlessly for a while - drawing mazes, creating trails are the recent ones. He says he just likes creating patterns in different ways, which I suppose makes sense.
Right - will continue to try and tiptoe around it!