Florist’s sponge is a great material for creating marks and patterns on. It squishes just to the shape of the tracks, so you’d better have a good set of them! try it out.
Jackie
does it change shape or swell after you paint it or apply a wash?
Any step-by step photos for us? 
-Muzzleflash
Florist’s sponge??? Oh you mean Oasis! It’s not really the best modelling material as it changes shape really easily. The slightest drop or nudge (for all you accident prone modellers out there!) will change its shape for good. Its not very responsive to paint either as it is used by florists to put plants in and is meant to absorb water. Puttys such as milliput or a celluclay mixture or half-dry model/body filler are great for permanent imprinting and if you get your timing right you won’t get any sticking to your tracks. Good luck and happy modelling!
yeah sounds too delicate for me 
-Muzzleflash
I think that when you do a diarama and you make it out of clay or plaster. While the clay or plaster is still soft you can press in with the tracks and you’ll get your track marks.
My son and I just used Sculptamold for the first time with his dinorama. The stuff dries hard within about 30 min or so. So as it sets up We pressed a set of tracks into it, some molding did stick to the tracks but washed off easyly. If we had waited for just a couple mins longer it would have been perfect. The Dinoramas track marks showed up great.
BTW the Sculptamold worked out great for our snow in the dinorama also.