is there a recipe i can use to make cookie dummies that i can use for display in the shop?

fake ones that won't mold in time?

If you make the NFS (no fail sugar cookies) recipe from this site and ice with royal icing, the cookies will hold up for eons.

You can spray them with clear lacquer after the royal dries for a shine, or paint them with thinned confectioners glaze.

Keep them in a fairly airtight, dry display and you'll get tired of looking at them before they go bad.

HTH
Rae

There's some kind of recipe (might have to search online) that they use to make Christmas ornaments from, that might work too...and then yeah, royal or even fondant or gumpaste.

I made some dracula cookies back in.......had to be 2006 or so and I still have one...it was no fail sugar cookies with mmf and fondant accents. I put it in a plastic cello bag and folded the top over and stapled it so it's not completely air tight and it still looks exactlly the same. I always try to make one extra cookie when I have an order so future customers can see an actual example of the size and decorations of certain cookies.

I have a NFSC with royal icing that is in a celo bag for a year now and it looks fine as well

I've made salt dough cookies for displays. They'll last for the rest of your natural life!