I made Chinese New Year. Normally it goes for something like a whole week but I made it three days instead. The first day traditions are cleaning and gardening (because my mother in law insists the house has to be spotless or else you'll have bad luck in the new year), then the second day is Chinese New Year Eve, it's traditions are drinking, baking, thankful spirit, make resolutions, and grand meal, and the last day is Chinese New Year, it's traditions are drinking, grand meal, invite guests, give gifts, and fireworks. (Now, the gifts are supposed to be money and only given to the children, but there's no option for that :( )
The next custom holiday I've made is Australia Day, it's traditions are water fun, party spirit, drinking, bbq, and fireworks.
And my last custom holiday is Spirit Day, it's traditions are attend holiday ceremony, rememberance, tell stories, and drinking.