I'll go into that in the first BOM, but you can use whatever really. FPP paper is very good, or freezer paper if you like see through, translucent vellum is also good but £££. Normal paper is also suitable (I use it for my spiral flying geese because it gets carried around a lot!). I do like the FPP paper, and it is a little easier to use than normal paper, but not enough that you can't do a good job without it.