I've switched to a 100mm macro on a tripod, aimed down, and a platform with a sheet of glass. I was catching the snowflakes on the glass but it's too large, difficult to position. I'm changing to a small 4 x 6 picture frame.
I use the tripod crank for the slider, then can hand focus, but the rail is a good suggestion.
Setup is on the Sun porch which is unheated. I can catch outside, bring in, and still be below freezing, but without the wind and chill.
Waiting for my package from China which might come before the Super Bowl. LOL
That's OK, I always have something cooking on another burner.
Star trails (thanks to RobHainer) Remote using for a time lapse of the cornfield (April to November = camera in a box) Close mic audio with a Zoom H2. Put the studio together in a spare room (music and photo) Auction next week, "electric guitar" might be of interest. And oh yes... edit photos. I'll never be done, sorting, culling and editing.

I've got a set of those cheap extension tubes. Did you pick up a macro focusing rail? If not, here's one for $11.65 USD with free shipping. It makes your life much easier! 