Are there any printed guidelines on how to build a TAPERED rock column.
Interesting. There are a number of old tapered house walls in old French villages. I was installing two cast metal lamp-poles, along my driveway, that came with hexagon shaped bases. I laid up rock bases, about 2 feet high, to mount the bases with conduit inside. I had no "guidelines" (and it shows!) but I did make cardboard hexagon cut-outs of various sizes to fit to the outside of the lay-up. The work came out looking a bit "free-hand" .... I just called it "character" and plunged ahead. I've gotten compliments on the work ... I suppose I have some polite neighbors.
My first question would be what is the intent of the column. Are they weight bearing or ornamental. The methods would be different for each. I just "googled" it and this is what I found. I would have my own specific depending on the intent but maybe this will give you some idea.
https://www.google.com/search?sourceid=navclient&ie=UTF-8&rlz=1T4TSNA_enUS401US438&q=building+tapered+stone+pillars
The ones the forest service builds that hold up a sign announcing the National Forest you're about to enter---they pour a square base, then build a simple tall, narrow pyramid out of plywood. Then they build a stone veneer over that out of native materials. The plywood probably just rots away over time, but most of them for Cleveland National Forest were built during the depression and are doing just fine