I have been asked a few times about this so here is a condensed version:
For templating I use:
1/8" x 2 7/8" x 8' luan. Then I stack them and chop-saw 25" (or 25 1/2") off the stack. Sometimes I pre-cut 45 degree angles if that template is going to use a few. Those are my counter 'depth' pieces. (One of my guys likes 1/8" MDF better "because it is not so 'slivery'"....wimp.) Sometimes, when I do an 'elevated' template ( on top of an existing counter ) I make blocks, about 3" high and hot-melt them along the front of the existing counter. They knock off easily after templating. That way you get to scribe the back wall on top of the back splash. The back of the counter I scribe with a Sharpie (gives me 1/4" offset) I assemble the template with a couple 3-M poly guns (hot-melt) Then, in strategic places, I cut the templates with 3" aviation snips and mark the template with all the important info..sink location, radius corners, finished edges etc. I also mark where all the gables are so I make sure there won't be a seam over the dishwasher...NEVER put a seam over the dishwasher. I include the overhang of the counter top in my template. (I used to do the cabinets only...some people just can't add 1 1/2".) I end up with chunks of template