hi is it possible to buy a pay as you go micro sim anywhere in chiang mai or do you need to get a normal sized one and cut it down ?

You will probably find it in some big department stores in town, like Robinson or Central Where they sell mobile phones .

Does anyone know if 1-2Call will be introducing a micro sim card?

They're not widely available but AIS, DTAC, and True will all swap your existing SIM for a micro SIM, either for free or for 50 Baht. Go to their main shops in Central Airport. I upgraded my True card there, the wife did her DTAC. Takes 2 minutes as they move your number from the old to the new SIM. The old SIM then stops working, obviously.

Yeh you can get one from any True move shop. If you don't want true move then you'll have to cut down your 12call sim like I did. It's doable but a bit tricky