He cast four rings for the four corners of the bronze grating, to provide places for the poles.
The rings are to be close to the frame to provide places for the poles to carry the table.
You are to make a grating for it, a network of bronze, and you are to make on the network four bronze rings on its four corners.
He made a grating for the altar, a network of bronze under its ledge, halfway up from the bottom.
He made the poles of acacia wood and overlaid them with bronze.