I bought two sets of Duff impression mats awhile back because they were on sale. I tried to use one of them on a cake and had two problems: (1) despite dusting with corn starch, the fondant stuck like crazy to the all of the little holes and (2) because the sheet is so small, whenever you impressed the next area, it ruins your first!!

WTH!? Can anyone help with using these, or are they just not worth it!?

I had the same problem. I ended up lightly spraying Pam on the mats for the sticking issue. Secondly, the size definitely is a problem. I cut all the sharp corners off, and each time I made an impression; I placed the mat as close to where I left off as possible. Not perfect, but that was my resolution.

HTH
Kat

Avoid the edges when making your imprint. Then scoot the mat over and try and line up. About as good as it gets. I luckily didn't have any sticking issue (with the wood grain one).

cute the edges off

lol cut*