I have been asked for a beer glass so how do I make the froth on the top?
I melted marshmellows with a little water in a greased bowl. Add a little coloring (I think I used brown) to get it foam colored. Pour into a container to set that is greased or lined somehow. HTH!
I just used fondant, because in my house the only right glass of beer is a perfectly poured glass, which means it doesn't foam over the top. That and Guinness is the choice, and the head (froth) is typically smoother and less bubbly.
Beer foam is pretty white, I wouldn't worry about color.
I just added a tiny bit so it was off white rather than bright white
I'm not so fussed about the colour just how to make it??
I did a Google search and found one helpful suggestion: use a small ice cream scoop (or you could use a cookie dough scoop) to scoop bc onto the cake. If you do a search in the CC galleries using "beer foam" in the search box, you'll find a number of pix of beer stein cakes. One in particular looks like the decorator used a large round tip and a whipped type of icing to create "blobs" of foam. Looked pretty realistic.