Butter Alternatives for Baking Pastry
There are good quality vegan margarines (Earth balance, Alsan) on the market nowadays, often they are of the interesterified instead of the hydrogenated variety. They are designed to behave and taste similar to butter instead of (as many cheap margarines seem to do) staying spreadable at temperatures where butter would be very firm. Unlike pure coconut or palm oil, they do not act very brittle when cold, and also they soften gradually instead of suddenly melting like eutectic solder. These should be on the top of the list of things to try...

Also, some recipes recommend using more than one type of fat in pastry, for more interesting texture (eg such margarine, and smaller flakes of a hardened coconut fat).