Patterning techniques Normally, by using a pen, I first draw the required design on the cushion foam. The patterns I would get would be with the real measures I already marked on the foam. I use two ways of patterning. One is by using 'stationery cardboard' in case of '2D flat designs', but if I have to pattern '3D irregular designs' I'd rather use 'stretchy vinyl'.
In both cases to keep them steady attached to the foam I use upholstery pins or some points of yellow glue. All of the patterns should match one in front of the other and I should not forget to mark where is necessary the 'alignment marks or notches'.
Why do I use 'stretchy vinyl' as a second option?
I use it in case of rounded areas, so I could stretch a little the material and pin there to not let it move. At the time of sewing procedure, I would stretch the material a little to make the 'notches' meet one in front of the other.
After having these 'real measures molds', is time to transfer them to 'real material (vinyl, leather, fabric, etc.)' not forgetting to add the 'seam allowance' that could be no less than 1 cm or 1/2 of an inch.
If i want to preserve these mold for similar jobs, I could transfer them to a 'thicker cardboard or thin sheet of metal'.
If more sophisticated, in case of laser cutting machines, I would transfer them to a computer.
I also have used in the past, the way of attaching the material to the seat by using upholstery pins and, directly mark with a tailor chalk or waxed pencil on the material giving it the required seam allowance. This method is valid but not so precise.