reed size

I found a source for willow reed nearby that seems to be reasonably priced. The problem is that I need to know what size reeds to buy for bannetons. The source I found has reeds in the following sizes.

1.25mm, 1.5mm, 1.75mm, 2.25mm, 2.75mm, 3.5mm, and 4.5 mm round diamaters.

It appears that they sell the reeds in 1-lb coils for $4 plus shipping.

Also, should I make the bottoms  with the coiled reed or use a plywood form for the bottom of the banneton? I already am aware that I should use stainless steel brads to hold the banneton together.

 Gordon