I lay the back smooth (but not taut) on a table, then add the batting, smooth it out and then add the (pressed) top. I took a little class that suggested putting a marble under the sandwich and rolling it to allow an Avery Dennison Micro-Fastener to be used every 4 inches. The micro-fasteners are small enough to hold the sandwich firmly together. The marble is low enough so as to not disturb the sandwich. I only had one small pucker that I could steam out. (You can get the marbles in a jar in the plant section of Michaels.) Also, does your Necchi have an addjustment for the bottom tension? I thought the one that I wore out had such an adjutment. Hope this helps. (Micro-Fasteners are available at Amazon.)