I do like Rob does--a faux trapunto on the quilting machine. I have basted some wool bat to an area of a quilt I want to be trapuntoed(?) so that the whole quilt was not double batted and it worked well too.

I have done channel trapunto where I stitch two fabrics together following an outline or applique pattern then thread cording or thick yarn into the channels between the two fabrics.

Anita Shackelford's book "Surface Textures" has a clear explanation of trapunto technique. It's an older book but has a lot of interesting surface design ideas. A lot of libraries have it.

Hand trapunto using a long needle and fluffy yarn is my favourite method. Years ago I tried Hari Walner's method from her book and hated it, but I admit I prefer hand work over machine work. The hand method using yarn is super easy and fast.

Two excellent tutorials for this method are Janet Treen's and Tim Latimer's.