I want to move the 9' x axis of my hotwire machine with either kevlar or steel reinforced timing belt.

If I put a small pulley on my stepper motor, connect that with a larger pulley making about a 3:1 ratio speed reduction, what do I use as an axle for the larger pulley?

How do I transfer this pulley to the longer belt on the axis?

And lastly, I will also need another axle for the idler pulley at the other end...where to purchase these?