Limestone pillar supports

Stalactites and stalagmites form naturally in caves, but take a long time to do so. If left long enough they will eventually join and form a limestone pillar.

It occurred to me that stalactite-like limestone pillars could be a decorative[1] architectural element, if only they could be acquired without distruction of rare and irreplacable[2] natural wonders.

I propose that such pillars may be grown much more quickly in optimal conditions, by 'farming' them. The pillars could be produced in standard sizes, and also grown to order. This would of course still take some time, but the starting point can be some way along in the process.
Allowing the use of a core cut from pre-existing limestone would greatly reduce the time needed, for non-purists. Probably only a few centimeters of growth would be necessary to cover this substrate.

The growing system would need to supply calcium- carbonate (CaCO3) saturated water to a point at the required height above the base level, in a dry atmosphere.
The optimum process temperature would need to be determined.
For a dissolved CaCO3 method, the water will need to be acidified with carbon dioxide (CO2), and the rate of growth may be increased if the atmosphere is low in CO2.
Given these points, a recycling system for water and CO2 would seem to be desirable, with moist, CO2-rich air from the growth chamber being bubbled through the dissolving tank.

Suggested environmentally friendly CaCO3 source: eggshells.

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[1] Possibly even load-bearing.

[2] on a human timescale.