I have made tarps for a while. Many shapes and sizes. I always cringe when someone says, can I have those curves... If I charged anyone to make stuff I would definitely charge extra for this. I hated either figuring out the template or cutting. I don't have a large area to lay it out flat and because they are always different I would have to do it for each one. I had not been smart enough to keep my templates. Well when putting in a recent order an offer popped up for a winter tarp template. At first I thought I wouldn't because I don't charge for the work, but only for materials. Then I thought I might treat myself and got it. Just cut a 12' winter tarp with cat cuts in about 10 minutes. Well worth it.
I would highly recommend putting tape down directly on the template, then applying tape to that for the project. It helps for adjustment and removal.