I let the form dry for a couple hours, then mixed my mud.
I used a premix sack of Type N morter that I have left over from attaching the rocks to the columns. I added two plastic cup fulls of Portland Cement and half a bottle of Charcoal die.
This mix is a result from advice I recieved on another thread called coloring cement.
I mixed half of the 60 pound sack and put it in kind of wet. Then I layed half inch, 19 guage, galvanized fenceing down.
Then I mixed the rest of the morter and added two more cups of cement to it. I put this in a little dryer to help hold it all together on the edges.
In the middle I placed a piece of 3/4 inch pvc to run my wire through when I install the cap.
The picture shows the hollow middle. I could have mixed another sack to fill it up, but I don't think I needed it. This is one full 60 pound sack.
I'm guessing I have about $10 into the cap, not counting lumber.