re: Making a form for an arch

is the router collet extension to carve the seat?
I need to buy yet another rabbet bit for the leg to seat joint.

So far I only made templates and cut the legs rough. I got stuck on making a 2 tones seat. I have not decided on the second "color ".
What I want to do is resaw the seat and add another wood between so when I carve the second color wood will come into view in some area.

This guy has some great dual tone chairs, you probably have seen his work already:
http://canadianwoodworks.com/gallery/rocking-chairs/#.U4fEz6ROW71