My daughters and I make these every year. You can change the look of the crystals by using different color and textures of pipe cleaners (chenille stems). Just choose your color and choose your shape: stars, snowflakes, trees, gingerbread men. The girls especially love using glittery white and silver ones to make 'snowflakes'.
We don't just do these at Christmas, either We've used them on our Christmas tree, to hang in our windows, to decorate packages and gift baskets, for grandparents, initials (fun to spell out the kids' names), mobiles, etc. One year we found red and white striped pipe cleaners and made really cute hearts for Valentine's Day to take with a plate of cookies to some shut-in's. They make darling flowers, too. The only limit is your imagination. :o) They are fairly sturdy but the crystals can be knocked off if hit too hard so we spray ours with clear acrylic spray paint/shellac when they're dry (especially the ornaments that we want to use year after year). We haven't tried adding food color to the water yet, but that's on our list of possible variations to see if it works the same. We have also tried reheating and reusing the solution, but with mixed results and you would need to dissolve more Borax in if you do that.