Budget Cone Domes
I just took a piece of thick carboard:
Cut a 15 inch circle out of it (used a string tied with a nail and pencil on each end--then poked the nail in the center to draw a perfect circle).
Then I folded the carboard in half in several directions to make it look like a bunch of pie shapes.
Then I cut from the center straight to the edge on one of the folds.
Then I overlapped the cardboard along the cut a couple of inches to make a cone and stapled (or tape) a few times along the edge.