I have these (the Sakura brand ones, right with the smiley cupcake on the front?).
These are not the ones that you heat to puff. They do just puff (a very teeny tiny bit) when you write with them. But the "puff" seems sort of fragile and might/will eventually squish down, I think. But they come in fun colors and I don't use them as often as I could.
I am sort of the "Puffy Stuff Queen" and use a few different products (with a heat tool) to get this effect. Two products I've used recently are "Liquid Applique" (Marvy) to get a low-rise, but definite 3D puff and Puffy Paint (Tulip) which REALLY puffs up when heated and ends up looks almost like shaving cream! (I was using white.) With both, but particularly the Tulip paint, you really have to be careful as it scorches incredibly quickly. The Marvy stuff can be hard to find (small tubes in a variety of about five basic colors) but good LSSs have it and I'm sure you could find it online. Any ACM/Mike's/Jo's or basic craft store has the Tulip paint with the fabric paints. The Tulip comes in more of a color variety. Probably about ten colors all together...
Good luck - these are all fun to play around with to get some different effects with your creative projects.
