I have a pair that I picked up at a Mast-fit clinic. Because they are flexible (You're talking about the microwavable footbeds, right?) I use them in my walking shoes. For this purpose they suit me just fine. Would I use them in my ski boots as a supportive insole? I could but I'm fairly flat footed with pronation - I prefer a custom because they offer more support under the heel with just the right amount of arch.
Molding the Zapz is the easy part, Just follow the directions. But trimming a foot bed is alittle tricky if you haven't done it before.