Need help/advice ref outdoor counter top

In need of guidance.

I am in the process of building an out door grill station. I wont call it a kitchen as there is no sink or water. I call myself planning it to death and beating a dead horse until failure.

I planned a stamped patio, natural gas for a fire pit, natural gas for a gas grill, electric, lighting, drainage, etc. I was able to complete the patio, a paver stone sitting wall, and a paver stone gas fire pit. Put in a manifold at the gas meter and ran gas around the house to the back yard. I went as far as designing an outdoor sound system with all the electronics out side, and a setup for out door movies. All that is done and works.

I built, with help from neighbor, the grill station. It's build out of paver wall stone to match the sitting wall and fire pit. This sits on top of the stamped patio. I put cement pillars in the ground under the patio for support and poured it thick.

My problem deals with the counter top. I have access to a neighbor that owns a granite company and can get granite. installed.

The out door grill station is curved and kinda long. There is no back splash however has two levels. left side and right side of the center section of the curve are the same level, the curve is one layer of stone taller. All lighting etc is done.

I have to make a TEMPLATE for the granite guys to "trace" and make the counter top. I have it down to where the seams will be and have put in angle iron for the support. do not know how to make the template and keep it clean, tight, and linear.

Does anyone have any experience of how to make an old fashion counter top template that can share the how to with me? I tried cutting thin 4ftx8ft sheets of plywood but it's so non straight it isn't funny. I need a two inch over hang and have no reference area to get a linear look. But to get all the cut outs and curve for each section and have it "line up".

I DON'T HAVE A CLUE.....Attached are some photos of different angles to see what I'm up against. Left to right, bge over drawer, grill over double doors, a side burner. raised section, counter top, under it, storage for firewood, right section counter top fridge underneath.

Thanks in advance