New Project - Cemetery Columns

Working on a new project this Labor Day to build out some Cemetery Columns.  I've seen many of these built but none quite having the 'gothic tomb' type of look I'm going after.

Here's the plan -- build a frame using 2x2 stock sheathed in 1/2" OSB.  Next, add some trim detail to top and bottom, with the top detail and cap using extruded foam board to save on weight.  To make the stonework I plan on covering the OSB with spackle/joint compound and then 'carve' out the mortar joints to get depth.  Then I'll seal and paint the whole thing to weather proof it and get the right aged look.

Still deciding what to put between the columns, but I'm leaning towards a gate constructed out of PVC similar in style to the existing fence.