For the past few years to create a winter scene on my SGMA modules, I have used without problems some readily available "Christmas drape" material. What I use is essentially white "batting" material with "sparkles" within it to simulate snow. The Christmas drape I use has silver sparkles but it can be purchased with multi-colored sparkles as well as without sparkles. This time of year you can find it available online and at most hobby/craft stores such as Hobby Lobby. You also can find it in the Christmas decoration sections of department stores such as Walmart. It comes in a wide range of rectangular and circular sizes suitable for building large or small Christmas Village scenes or for use as skirting under a Christmas tree. The brand I used said it was flame retardant but I never tested it.
For the SGMA layouts at Trainfest 2012 in Milwaukee and at the Oklahoma City Train Show this year, I cut up several large Christmas drapes in order to cover the green carpet on several of my SGMA modules with simulated sparkling snow. This included the placement of long narrow strips of the material between SGMA's three mainlines. Over this material was then placed a variety of Standard Gauge-sized Christmas "putz" (cardboard) houses as well as numerous test tube brush Chistmas trees. Looked GREAT!
In four days of constant running at both shows only one minor problem occured when one of the narrow strips of the batting between two mainlines caught on a freight car and was briefly dragged along the mainline. No damage was done and the problem was quickly fixed.
Bob