I start the pattern by laying out the two top lines on either side of the forend. These need to be the exact same length and in the very same position. These are laid out with wooden jig and a dog leg scribe. I then use a 60 degree cutter to deepen these two boarders. Then using a piece of copy paper I have wrapped around the forend I mark the ends of both these freshly cut lines as accurately as possible with the paper immobile and very taught. I use this marked paper to give me the volume of the forend in the length of the pattern to be cut. I find and establish the centerline based on the forends volume and add a 3" to 1" set of master lines on this template and draw in the pattern I want to transfer to the stock. All the boarders are laid out on this paper template.
When I have the pattern exactly like I want it tape it to the stocks forend and transfer the pattern to the wood with a tiny prick punch. When the entire transfer is complete I remove the paper and using baby powder to highlight the pricked holes make sure all is well. Changing anything at this stage is very difficult so diligence and accuracy while making the paper pattern and in the transfer is very important. Using the same 60 degree cutter I cut in both master lines and begin cutting in the lines with both a 2 and a 3 line cutters that cut on the pull stroke. All the teeth are cutting teeth, I do not like the safe edge cutters. I will space 4 lines in a singular direction then reverse the stock 180 degrees and cut in 4 more lines from the opposite direction and on either side of the pattern. When I'm spacing the pattern I do so standing up otherwise I tend to allow my lines to drift if I'm sitting. I also layout lines parallel to the master lines around the forend to check from time to time to keep me in sync with the desired results. If my lines start drifting I make corrections at that time.