If you don't have a table that will work and are laying everything out on carpet, you can use T-Pins. I use a table with clamps for my full size down quilts, but bigger quilts go on the floor. I lay out the backing and use T-Pins to pin it flat onto the carpet, then the batting is T-Pinned, and the top is T-Pinned until I am done sandwiching with the safety pins. You just have to make sure you get your safety pins all the way through without pinning it all to the carpet.